diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 6a4ed6e..70979a2 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -387,6 +387,7 @@
     reader/wgsl/parser_impl_switch_body_test.cc
     reader/wgsl/parser_impl_switch_stmt_test.cc
     reader/wgsl/parser_impl_test.cc
+    reader/wgsl/parser_impl_test_helper.h
     reader/wgsl/parser_impl_type_alias_test.cc
     reader/wgsl/parser_impl_type_decl_test.cc
     reader/wgsl/parser_impl_unary_expression_test.cc
diff --git a/src/context.h b/src/context.h
new file mode 100644
index 0000000..868f069
--- /dev/null
+++ b/src/context.h
@@ -0,0 +1,28 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_CONTEXT_H_
+#define SRC_CONTEXT_H_
+
+#include "src/type_manager.h"
+
+namespace tint {
+
+struct Context {
+  TypeManager* type_mgr = nullptr;
+};
+
+}  // namespace tint
+
+#endif  // SRC_CONTEXT_H_
diff --git a/src/reader/reader.cc b/src/reader/reader.cc
index 6d90273..064482e 100644
--- a/src/reader/reader.cc
+++ b/src/reader/reader.cc
@@ -17,7 +17,7 @@
 namespace tint {
 namespace reader {
 
-Reader::Reader() = default;
+Reader::Reader(const Context& ctx) : ctx_(ctx) {}
 
 Reader::~Reader() = default;
 
diff --git a/src/reader/reader.h b/src/reader/reader.h
index 8aa48d5..a3dbbf5 100644
--- a/src/reader/reader.h
+++ b/src/reader/reader.h
@@ -18,6 +18,7 @@
 #include <string>
 
 #include "src/ast/module.h"
+#include "src/context.h"
 
 namespace tint {
 namespace reader {
@@ -41,12 +42,16 @@
 
  protected:
   /// Constructor
-  Reader();
+  /// @param ctx the context object
+  explicit Reader(const Context& ctx);
 
   /// Sets the error string
   /// @param msg the error message
   void set_error(const std::string& msg) { error_ = msg; }
 
+  /// The Tint context object
+  const Context& ctx_;
+
   /// An error message, if an error was encountered
   std::string error_;
 };
diff --git a/src/reader/spirv/parser.cc b/src/reader/spirv/parser.cc
index 46e4433..8b3bd44 100644
--- a/src/reader/spirv/parser.cc
+++ b/src/reader/spirv/parser.cc
@@ -20,8 +20,8 @@
 namespace reader {
 namespace spirv {
 
-Parser::Parser(const std::vector<uint32_t>& spv_binary)
-    : Reader(), impl_(std::make_unique<ParserImpl>(spv_binary)) {}
+Parser::Parser(const Context& ctx, const std::vector<uint32_t>& spv_binary)
+    : Reader(ctx), impl_(std::make_unique<ParserImpl>(ctx, spv_binary)) {}
 
 Parser::~Parser() = default;
 
diff --git a/src/reader/spirv/parser.h b/src/reader/spirv/parser.h
index 0ace60c..d5c41c2 100644
--- a/src/reader/spirv/parser.h
+++ b/src/reader/spirv/parser.h
@@ -31,8 +31,9 @@
 class Parser : public Reader {
  public:
   /// Creates a new parser
+  /// @param ctx the context object
   /// @param input the input data to parse
-  explicit Parser(const std::vector<uint32_t>& input);
+  Parser(const Context& ctx, const std::vector<uint32_t>& input);
   /// Destructor
   ~Parser() override;
 
diff --git a/src/reader/spirv/parser_impl.cc b/src/reader/spirv/parser_impl.cc
index 81aa8d8..000cd64 100644
--- a/src/reader/spirv/parser_impl.cc
+++ b/src/reader/spirv/parser_impl.cc
@@ -44,8 +44,9 @@
 
 }  // namespace
 
-ParserImpl::ParserImpl(const std::vector<uint32_t>& spv_binary)
-    : Reader(),
+ParserImpl::ParserImpl(const Context& ctx,
+                       const std::vector<uint32_t>& spv_binary)
+    : Reader(ctx),
       spv_binary_(spv_binary),
       fail_stream_(&success_, &errors_),
       namer_(fail_stream_),
@@ -75,6 +76,11 @@
 ParserImpl::~ParserImpl() = default;
 
 bool ParserImpl::Parse() {
+  if (ctx_.type_mgr == nullptr) {
+    Fail() << "Missing type manager";
+    return false;
+  }
+
   if (!success_) {
     return false;
   }
@@ -125,22 +131,21 @@
   }
 
   ast::type::Type* result = nullptr;
-  TypeManager* tint_tm = TypeManager::Instance();
 
   switch (spirv_type->kind()) {
     case spvtools::opt::analysis::Type::kVoid:
-      result = tint_tm->Get(std::make_unique<ast::type::VoidType>());
+      result = ctx_.type_mgr->Get(std::make_unique<ast::type::VoidType>());
       break;
     case spvtools::opt::analysis::Type::kBool:
-      result = tint_tm->Get(std::make_unique<ast::type::BoolType>());
+      result = ctx_.type_mgr->Get(std::make_unique<ast::type::BoolType>());
       break;
     case spvtools::opt::analysis::Type::kInteger: {
       const auto* int_ty = spirv_type->AsInteger();
       if (int_ty->width() == 32) {
         if (int_ty->IsSigned()) {
-          result = tint_tm->Get(std::make_unique<ast::type::I32Type>());
+          result = ctx_.type_mgr->Get(std::make_unique<ast::type::I32Type>());
         } else {
-          result = tint_tm->Get(std::make_unique<ast::type::U32Type>());
+          result = ctx_.type_mgr->Get(std::make_unique<ast::type::U32Type>());
         }
       } else {
         Fail() << "unhandled integer width: " << int_ty->width();
@@ -150,7 +155,7 @@
     case spvtools::opt::analysis::Type::kFloat: {
       const auto* float_ty = spirv_type->AsFloat();
       if (float_ty->width() == 32) {
-        result = tint_tm->Get(std::make_unique<ast::type::F32Type>());
+        result = ctx_.type_mgr->Get(std::make_unique<ast::type::F32Type>());
       } else {
         Fail() << "unhandled float width: " << float_ty->width();
       }
@@ -161,7 +166,7 @@
       const auto num_elem = vec_ty->element_count();
       auto* ast_elem_ty = ConvertType(type_mgr_->GetId(vec_ty->element_type()));
       if (ast_elem_ty != nullptr) {
-        result = tint_tm->Get(
+        result = ctx_.type_mgr->Get(
             std::make_unique<ast::type::VectorType>(ast_elem_ty, num_elem));
       }
       // In the error case, we'll already have emitted a diagnostic.
@@ -175,7 +180,7 @@
       const auto num_columns = mat_ty->element_count();
       auto* ast_scalar_ty = ConvertType(type_mgr_->GetId(scalar_ty));
       if (ast_scalar_ty != nullptr) {
-        result = tint_tm->Get(std::make_unique<ast::type::MatrixType>(
+        result = ctx_.type_mgr->Get(std::make_unique<ast::type::MatrixType>(
             ast_scalar_ty, num_rows, num_columns));
       }
       // In the error case, we'll already have emitted a diagnostic.
diff --git a/src/reader/spirv/parser_impl.h b/src/reader/spirv/parser_impl.h
index f5bfc04..d7487c5 100644
--- a/src/reader/spirv/parser_impl.h
+++ b/src/reader/spirv/parser_impl.h
@@ -45,8 +45,9 @@
 class ParserImpl : Reader {
  public:
   /// Creates a new parser
+  /// @param ctx the context object
   /// @param input the input data to parse
-  explicit ParserImpl(const std::vector<uint32_t>& input);
+  ParserImpl(const Context& ctx, const std::vector<uint32_t>& input);
   /// Destructor
   ~ParserImpl() override;
 
diff --git a/src/reader/spirv/parser_impl_convert_type_test.cc b/src/reader/spirv/parser_impl_convert_type_test.cc
index dd16e0a..4a0dfdf 100644
--- a/src/reader/spirv/parser_impl_convert_type_test.cc
+++ b/src/reader/spirv/parser_impl_convert_type_test.cc
@@ -20,6 +20,7 @@
 #include "src/ast/type/matrix_type.h"
 #include "src/ast/type/vector_type.h"
 #include "src/reader/spirv/parser_impl.h"
+#include "src/reader/spirv/parser_impl_test_helper.h"
 #include "src/reader/spirv/spirv_tools_helpers_test.h"
 #include "src/type_manager.h"
 
@@ -30,231 +31,224 @@
 
 using ::testing::Eq;
 
-class SpvParserTest_ConvertType : public ::testing::Test {
-  void TearDown() override {
-    // Clean up the type manager instance at the end of a single test.
-    TypeManager::Destroy();
-  }
-};
-
-TEST_F(SpvParserTest_ConvertType, PreservesExistingFailure) {
-  ParserImpl p(std::vector<uint32_t>{});
-  p.Fail() << "boing";
-  auto* type = p.ConvertType(10);
+TEST_F(SpvParserTest, ConvertType_PreservesExistingFailure) {
+  auto p = parser(std::vector<uint32_t>{});
+  p->Fail() << "boing";
+  auto* type = p->ConvertType(10);
   EXPECT_EQ(type, nullptr);
-  EXPECT_THAT(p.error(), Eq("boing"));
+  EXPECT_THAT(p->error(), Eq("boing"));
 }
 
-TEST_F(SpvParserTest_ConvertType, RequiresInternalRepresntation) {
-  ParserImpl p(std::vector<uint32_t>{});
-  auto* type = p.ConvertType(10);
+TEST_F(SpvParserTest, ConvertType_RequiresInternalRepresntation) {
+  auto p = parser(std::vector<uint32_t>{});
+  auto* type = p->ConvertType(10);
   EXPECT_EQ(type, nullptr);
   EXPECT_THAT(
-      p.error(),
+      p->error(),
       Eq("ConvertType called when the internal module has not been built"));
 }
 
-TEST_F(SpvParserTest_ConvertType, NotAnId) {
-  ParserImpl p(test::Assemble("%1 = OpExtInstImport \"GLSL.std.450\""));
-  EXPECT_TRUE(p.BuildAndParseInternalModule()) << p.error();
+TEST_F(SpvParserTest, ConvertType_NotAnId) {
+  auto p = parser(test::Assemble("%1 = OpExtInstImport \"GLSL.std.450\""));
+  EXPECT_TRUE(p->BuildAndParseInternalModule()) << p->error();
 
-  auto* type = p.ConvertType(10);
+  auto* type = p->ConvertType(10);
   EXPECT_EQ(type, nullptr);
   EXPECT_EQ(nullptr, type);
-  EXPECT_THAT(p.error(), Eq("ID is not a SPIR-V type: 10"));
+  EXPECT_THAT(p->error(), Eq("ID is not a SPIR-V type: 10"));
 }
 
-TEST_F(SpvParserTest_ConvertType, IdExistsButIsNotAType) {
-  ParserImpl p(test::Assemble("%1 = OpExtInstImport \"GLSL.std.450\""));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_IdExistsButIsNotAType) {
+  auto p = parser(test::Assemble("%1 = OpExtInstImport \"GLSL.std.450\""));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(1);
+  auto* type = p->ConvertType(1);
   EXPECT_EQ(nullptr, type);
-  EXPECT_THAT(p.error(), Eq("ID is not a SPIR-V type: 1"));
+  EXPECT_THAT(p->error(), Eq("ID is not a SPIR-V type: 1"));
 }
 
-TEST_F(SpvParserTest_ConvertType, UnhandledType) {
+TEST_F(SpvParserTest, ConvertType_UnhandledType) {
   // Pipes are an OpenCL type. Tint doesn't support them.
-  ParserImpl p(test::Assemble("%70 = OpTypePipe WriteOnly"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  auto p = parser(test::Assemble("%70 = OpTypePipe WriteOnly"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(70);
+  auto* type = p->ConvertType(70);
   EXPECT_EQ(nullptr, type);
-  EXPECT_THAT(p.error(), Eq("unknown SPIR-V type: 70"));
+  EXPECT_THAT(p->error(), Eq("unknown SPIR-V type: 70"));
 }
 
-TEST_F(SpvParserTest_ConvertType, Void) {
-  ParserImpl p(test::Assemble("%1 = OpTypeVoid"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_Void) {
+  auto p = parser(test::Assemble("%1 = OpTypeVoid"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(1);
+  auto* type = p->ConvertType(1);
   EXPECT_TRUE(type->IsVoid());
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, Bool) {
-  ParserImpl p(test::Assemble("%100 = OpTypeBool"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_Bool) {
+  auto p = parser(test::Assemble("%100 = OpTypeBool"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(100);
+  auto* type = p->ConvertType(100);
   EXPECT_TRUE(type->IsBool());
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, I32) {
-  ParserImpl p(test::Assemble("%2 = OpTypeInt 32 1"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_I32) {
+  auto p = parser(test::Assemble("%2 = OpTypeInt 32 1"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(2);
+  auto* type = p->ConvertType(2);
   EXPECT_TRUE(type->IsI32());
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, U32) {
-  ParserImpl p(test::Assemble("%3 = OpTypeInt 32 0"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_U32) {
+  auto p = parser(test::Assemble("%3 = OpTypeInt 32 0"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(3);
+  auto* type = p->ConvertType(3);
   EXPECT_TRUE(type->IsU32());
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, F32) {
-  ParserImpl p(test::Assemble("%4 = OpTypeFloat 32"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_F32) {
+  auto p = parser(test::Assemble("%4 = OpTypeFloat 32"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(4);
+  auto* type = p->ConvertType(4);
   EXPECT_TRUE(type->IsF32());
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, BadIntWidth) {
-  ParserImpl p(test::Assemble("%5 = OpTypeInt 17 1"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_BadIntWidth) {
+  auto p = parser(test::Assemble("%5 = OpTypeInt 17 1"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(5);
+  auto* type = p->ConvertType(5);
   EXPECT_EQ(type, nullptr);
-  EXPECT_THAT(p.error(), Eq("unhandled integer width: 17"));
+  EXPECT_THAT(p->error(), Eq("unhandled integer width: 17"));
 }
 
-TEST_F(SpvParserTest_ConvertType, BadFloatWidth) {
-  ParserImpl p(test::Assemble("%6 = OpTypeFloat 19"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+TEST_F(SpvParserTest, ConvertType_BadFloatWidth) {
+  auto p = parser(test::Assemble("%6 = OpTypeFloat 19"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(6);
+  auto* type = p->ConvertType(6);
   EXPECT_EQ(type, nullptr);
-  EXPECT_THAT(p.error(), Eq("unhandled float width: 19"));
+  EXPECT_THAT(p->error(), Eq("unhandled float width: 19"));
 }
 
-TEST_F(SpvParserTest_ConvertType, InvalidVectorElement) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, DISABLED_ConvertType_InvalidVectorElement) {
+  auto p = parser(test::Assemble(R"(
     %5 = OpTypePipe ReadOnly
     %20 = OpTypeVector %5 2
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(20);
+  auto* type = p->ConvertType(20);
   EXPECT_EQ(type, nullptr);
-  EXPECT_THAT(p.error(), Eq("unknown SPIR-V type: 5"));
+  EXPECT_THAT(p->error(), Eq("unknown SPIR-V type: 5"));
 }
 
-TEST_F(SpvParserTest_ConvertType, VecOverF32) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, ConvertType_VecOverF32) {
+  auto p = parser(test::Assemble(R"(
     %float = OpTypeFloat 32
     %20 = OpTypeVector %float 2
     %30 = OpTypeVector %float 3
     %40 = OpTypeVector %float 4
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* v2xf32 = p.ConvertType(20);
+  auto* v2xf32 = p->ConvertType(20);
   EXPECT_TRUE(v2xf32->IsVector());
   EXPECT_TRUE(v2xf32->AsVector()->type()->IsF32());
   EXPECT_EQ(v2xf32->AsVector()->size(), 2u);
 
-  auto* v3xf32 = p.ConvertType(30);
+  auto* v3xf32 = p->ConvertType(30);
   EXPECT_TRUE(v3xf32->IsVector());
   EXPECT_TRUE(v3xf32->AsVector()->type()->IsF32());
   EXPECT_EQ(v3xf32->AsVector()->size(), 3u);
 
-  auto* v4xf32 = p.ConvertType(40);
+  auto* v4xf32 = p->ConvertType(40);
   EXPECT_TRUE(v4xf32->IsVector());
   EXPECT_TRUE(v4xf32->AsVector()->type()->IsF32());
   EXPECT_EQ(v4xf32->AsVector()->size(), 4u);
 
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, VecOverI32) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, ConvertType_VecOverI32) {
+  auto p = parser(test::Assemble(R"(
     %int = OpTypeInt 32 1
     %20 = OpTypeVector %int 2
     %30 = OpTypeVector %int 3
     %40 = OpTypeVector %int 4
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* v2xi32 = p.ConvertType(20);
+  auto* v2xi32 = p->ConvertType(20);
   EXPECT_TRUE(v2xi32->IsVector());
   EXPECT_TRUE(v2xi32->AsVector()->type()->IsI32());
   EXPECT_EQ(v2xi32->AsVector()->size(), 2u);
 
-  auto* v3xi32 = p.ConvertType(30);
+  auto* v3xi32 = p->ConvertType(30);
   EXPECT_TRUE(v3xi32->IsVector());
   EXPECT_TRUE(v3xi32->AsVector()->type()->IsI32());
   EXPECT_EQ(v3xi32->AsVector()->size(), 3u);
 
-  auto* v4xi32 = p.ConvertType(40);
+  auto* v4xi32 = p->ConvertType(40);
   EXPECT_TRUE(v4xi32->IsVector());
   EXPECT_TRUE(v4xi32->AsVector()->type()->IsI32());
   EXPECT_EQ(v4xi32->AsVector()->size(), 4u);
 
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, VecOverU32) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, ConvertType_VecOverU32) {
+  auto p = parser(test::Assemble(R"(
     %uint = OpTypeInt 32 0
     %20 = OpTypeVector %uint 2
     %30 = OpTypeVector %uint 3
     %40 = OpTypeVector %uint 4
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* v2xu32 = p.ConvertType(20);
+  auto* v2xu32 = p->ConvertType(20);
   EXPECT_TRUE(v2xu32->IsVector());
   EXPECT_TRUE(v2xu32->AsVector()->type()->IsU32());
   EXPECT_EQ(v2xu32->AsVector()->size(), 2u);
 
-  auto* v3xu32 = p.ConvertType(30);
+  auto* v3xu32 = p->ConvertType(30);
   EXPECT_TRUE(v3xu32->IsVector());
   EXPECT_TRUE(v3xu32->AsVector()->type()->IsU32());
   EXPECT_EQ(v3xu32->AsVector()->size(), 3u);
 
-  auto* v4xu32 = p.ConvertType(40);
+  auto* v4xu32 = p->ConvertType(40);
   EXPECT_TRUE(v4xu32->IsVector());
   EXPECT_TRUE(v4xu32->AsVector()->type()->IsU32());
   EXPECT_EQ(v4xu32->AsVector()->size(), 4u);
 
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
-TEST_F(SpvParserTest_ConvertType, InvalidMatrixElement) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, DISABLED_ConvertType_InvalidMatrixElement) {
+  auto p = parser(test::Assemble(R"(
     %5 = OpTypePipe ReadOnly
     %10 = OpTypeVector %5 2
     %20 = OpTypeMatrix %10 2
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* type = p.ConvertType(20);
+  auto* type = p->ConvertType(20);
   EXPECT_EQ(type, nullptr);
-  EXPECT_THAT(p.error(), Eq("unknown SPIR-V type: 5"));
+  EXPECT_THAT(p->error(), Eq("unknown SPIR-V type: 5"));
 }
 
-TEST_F(SpvParserTest_ConvertType, MatrixOverF32) {
+TEST_F(SpvParserTest, ConvertType_MatrixOverF32) {
   // Matrices are only defined over floats.
-  ParserImpl p(test::Assemble(R"(
+  auto p = parser(test::Assemble(R"(
     %float = OpTypeFloat 32
     %v2 = OpTypeVector %float 2
     %v3 = OpTypeVector %float 3
@@ -271,63 +265,63 @@
     %43 = OpTypeMatrix %v4 3
     %44 = OpTypeMatrix %v4 4
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
 
-  auto* m22 = p.ConvertType(22);
+  auto* m22 = p->ConvertType(22);
   EXPECT_TRUE(m22->IsMatrix());
   EXPECT_TRUE(m22->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m22->AsMatrix()->rows(), 2);
   EXPECT_EQ(m22->AsMatrix()->columns(), 2);
 
-  auto* m23 = p.ConvertType(23);
+  auto* m23 = p->ConvertType(23);
   EXPECT_TRUE(m23->IsMatrix());
   EXPECT_TRUE(m23->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m23->AsMatrix()->rows(), 2);
   EXPECT_EQ(m23->AsMatrix()->columns(), 3);
 
-  auto* m24 = p.ConvertType(24);
+  auto* m24 = p->ConvertType(24);
   EXPECT_TRUE(m24->IsMatrix());
   EXPECT_TRUE(m24->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m24->AsMatrix()->rows(), 2);
   EXPECT_EQ(m24->AsMatrix()->columns(), 4);
 
-  auto* m32 = p.ConvertType(32);
+  auto* m32 = p->ConvertType(32);
   EXPECT_TRUE(m32->IsMatrix());
   EXPECT_TRUE(m32->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m32->AsMatrix()->rows(), 3);
   EXPECT_EQ(m32->AsMatrix()->columns(), 2);
 
-  auto* m33 = p.ConvertType(33);
+  auto* m33 = p->ConvertType(33);
   EXPECT_TRUE(m33->IsMatrix());
   EXPECT_TRUE(m33->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m33->AsMatrix()->rows(), 3);
   EXPECT_EQ(m33->AsMatrix()->columns(), 3);
 
-  auto* m34 = p.ConvertType(34);
+  auto* m34 = p->ConvertType(34);
   EXPECT_TRUE(m34->IsMatrix());
   EXPECT_TRUE(m34->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m34->AsMatrix()->rows(), 3);
   EXPECT_EQ(m34->AsMatrix()->columns(), 4);
 
-  auto* m42 = p.ConvertType(42);
+  auto* m42 = p->ConvertType(42);
   EXPECT_TRUE(m42->IsMatrix());
   EXPECT_TRUE(m42->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m42->AsMatrix()->rows(), 4);
   EXPECT_EQ(m42->AsMatrix()->columns(), 2);
 
-  auto* m43 = p.ConvertType(43);
+  auto* m43 = p->ConvertType(43);
   EXPECT_TRUE(m43->IsMatrix());
   EXPECT_TRUE(m43->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m43->AsMatrix()->rows(), 4);
   EXPECT_EQ(m43->AsMatrix()->columns(), 3);
 
-  auto* m44 = p.ConvertType(44);
+  auto* m44 = p->ConvertType(44);
   EXPECT_TRUE(m44->IsMatrix());
   EXPECT_TRUE(m44->AsMatrix()->type()->IsF32());
   EXPECT_EQ(m44->AsMatrix()->rows(), 4);
   EXPECT_EQ(m44->AsMatrix()->columns(), 4);
 
-  EXPECT_TRUE(p.error().empty());
+  EXPECT_TRUE(p->error().empty());
 }
 
 }  // namespace
diff --git a/src/reader/spirv/parser_impl_entry_point_test.cc b/src/reader/spirv/parser_impl_entry_point_test.cc
index a678576..c216b3b 100644
--- a/src/reader/spirv/parser_impl_entry_point_test.cc
+++ b/src/reader/spirv/parser_impl_entry_point_test.cc
@@ -16,6 +16,7 @@
 
 #include "gmock/gmock.h"
 #include "src/reader/spirv/parser_impl.h"
+#include "src/reader/spirv/parser_impl_test_helper.h"
 #include "src/reader/spirv/spirv_tools_helpers_test.h"
 
 namespace tint {
@@ -25,8 +26,6 @@
 
 using ::testing::HasSubstr;
 
-using SpvParserTest_EntryPoint = ::testing::Test;
-
 std::string MakeEntryPoint(const std::string& stage,
                            const std::string& name,
                            const std::string& id = "42") {
@@ -35,55 +34,55 @@
          "%" + id + " = OpTypeVoid\n";
 }
 
-TEST_F(SpvParserTest_EntryPoint, NoEntryPoint) {
-  ParserImpl p(test::Assemble(""));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_ast = p.module().to_str();
+TEST_F(SpvParserTest, EntryPoint_NoEntryPoint) {
+  auto p = parser(test::Assemble(""));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_ast = p->module().to_str();
   EXPECT_THAT(module_ast, Not(HasSubstr("EntryPoint")));
 }
 
-TEST_F(SpvParserTest_EntryPoint, Vertex) {
-  ParserImpl p(test::Assemble(MakeEntryPoint("Vertex", "foobar")));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_str = p.module().to_str();
+TEST_F(SpvParserTest, EntryPoint_Vertex) {
+  auto p = parser(test::Assemble(MakeEntryPoint("Vertex", "foobar")));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{vertex = foobar})"));
 }
 
-TEST_F(SpvParserTest_EntryPoint, Fragment) {
-  ParserImpl p(test::Assemble(MakeEntryPoint("Fragment", "blitz")));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_str = p.module().to_str();
+TEST_F(SpvParserTest, EntryPoint_Fragment) {
+  auto p = parser(test::Assemble(MakeEntryPoint("Fragment", "blitz")));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{fragment = blitz})"));
 }
 
-TEST_F(SpvParserTest_EntryPoint, Compute) {
-  ParserImpl p(test::Assemble(MakeEntryPoint("GLCompute", "sort")));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_str = p.module().to_str();
+TEST_F(SpvParserTest, EntryPoint_Compute) {
+  auto p = parser(test::Assemble(MakeEntryPoint("GLCompute", "sort")));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{compute = sort})"));
 }
 
-TEST_F(SpvParserTest_EntryPoint, MultiNameConflict) {
-  ParserImpl p(test::Assemble(MakeEntryPoint("GLCompute", "work", "40") +
-                              MakeEntryPoint("Vertex", "work", "50") +
-                              MakeEntryPoint("Fragment", "work", "60")));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_str = p.module().to_str();
+TEST_F(SpvParserTest, EntryPoint_MultiNameConflict) {
+  auto p = parser(test::Assemble(MakeEntryPoint("GLCompute", "work", "40") +
+                                 MakeEntryPoint("Vertex", "work", "50") +
+                                 MakeEntryPoint("Fragment", "work", "60")));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{compute = work})"));
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{vertex = work_1})"));
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{fragment = work_2})"));
 }
 
-TEST_F(SpvParserTest_EntryPoint, NameIsSanitized) {
-  ParserImpl p(test::Assemble(MakeEntryPoint("GLCompute", ".1234")));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_str = p.module().to_str();
+TEST_F(SpvParserTest, EntryPoint_NameIsSanitized) {
+  auto p = parser(test::Assemble(MakeEntryPoint("GLCompute", ".1234")));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_str = p->module().to_str();
   EXPECT_THAT(module_str, HasSubstr(R"(EntryPoint{compute = x_1234})"));
 }
 
diff --git a/src/reader/spirv/parser_impl_import_test.cc b/src/reader/spirv/parser_impl_import_test.cc
index 772c299..4febd6e 100644
--- a/src/reader/spirv/parser_impl_import_test.cc
+++ b/src/reader/spirv/parser_impl_import_test.cc
@@ -17,6 +17,7 @@
 
 #include "gmock/gmock.h"
 #include "src/reader/spirv/parser_impl.h"
+#include "src/reader/spirv/parser_impl_test_helper.h"
 #include "src/reader/spirv/spirv_tools_helpers_test.h"
 
 namespace tint {
@@ -30,34 +31,32 @@
 using ::testing::Not;
 using ::testing::UnorderedElementsAre;
 
-using SpvParseImport = ::testing::Test;
-
-TEST_F(SpvParseImport, NoImport) {
-  ParserImpl p(test::Assemble("%1 = OpTypeVoid"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  const auto module_ast = p.module().to_str();
+TEST_F(SpvParserTest, Import_NoImport) {
+  auto p = parser(test::Assemble("%1 = OpTypeVoid"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  const auto module_ast = p->module().to_str();
   EXPECT_THAT(module_ast, Not(HasSubstr("Import")));
 }
 
-TEST_F(SpvParseImport, ImportGlslStd450) {
-  ParserImpl p(test::Assemble(R"(%1 = OpExtInstImport "GLSL.std.450")"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  EXPECT_THAT(p.glsl_std_450_imports(), ElementsAre(1));
-  const auto module_ast = p.module().to_str();
+TEST_F(SpvParserTest, Import_ImportGlslStd450) {
+  auto p = parser(test::Assemble(R"(%1 = OpExtInstImport "GLSL.std.450")"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  EXPECT_THAT(p->glsl_std_450_imports(), ElementsAre(1));
+  const auto module_ast = p->module().to_str();
   EXPECT_THAT(module_ast, HasSubstr(R"(Import{"GLSL.std.450" as std::glsl})"));
 }
 
-TEST_F(SpvParseImport, ImportGlslStd450Twice) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, Import_ImportGlslStd450Twice) {
+  auto p = parser(test::Assemble(R"(
     %1  = OpExtInstImport "GLSL.std.450"
     %42 = OpExtInstImport "GLSL.std.450"
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_TRUE(p.error().empty());
-  EXPECT_THAT(p.glsl_std_450_imports(), UnorderedElementsAre(1, 42));
-  const auto module = p.module();
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_TRUE(p->error().empty());
+  EXPECT_THAT(p->glsl_std_450_imports(), UnorderedElementsAre(1, 42));
+  const auto module = p->module();
   EXPECT_EQ(module.imports().size(), 1);
   const auto module_ast = module.to_str();
   // TODO(dneto): Use a matcher to show there is only one import.
diff --git a/src/reader/spirv/parser_impl_test.cc b/src/reader/spirv/parser_impl_test.cc
index c4ce36c..6a05413 100644
--- a/src/reader/spirv/parser_impl_test.cc
+++ b/src/reader/spirv/parser_impl_test.cc
@@ -18,6 +18,7 @@
 #include <vector>
 
 #include "gmock/gmock.h"
+#include "src/reader/spirv/parser_impl_test_helper.h"
 #include "src/reader/spirv/spirv_tools_helpers_test.h"
 
 namespace tint {
@@ -28,23 +29,21 @@
 
 using ::testing::HasSubstr;
 
-using SpvParserImplTest = testing::Test;
-
-TEST_F(SpvParserImplTest, Uint32VecEmpty) {
+TEST_F(SpvParserTest, Impl_Uint32VecEmpty) {
   std::vector<uint32_t> data;
-  ParserImpl p{data};
-  EXPECT_FALSE(p.Parse());
+  auto p = parser(data);
+  EXPECT_FALSE(p->Parse());
   // TODO(dneto): What message?
 }
 
-TEST_F(SpvParserImplTest, InvalidModuleFails) {
+TEST_F(SpvParserTest, Impl_InvalidModuleFails) {
   auto invalid_spv = test::Assemble("%ty = OpTypeInt 3 0");
-  ParserImpl p{invalid_spv};
-  EXPECT_FALSE(p.Parse());
+  auto p = parser(invalid_spv);
+  EXPECT_FALSE(p->Parse());
   EXPECT_THAT(
-      p.error(),
+      p->error(),
       HasSubstr("TypeInt cannot appear before the memory model instruction"));
-  EXPECT_THAT(p.error(), HasSubstr("OpTypeInt 3 0"));
+  EXPECT_THAT(p->error(), HasSubstr("OpTypeInt 3 0"));
 }
 
 // TODO(dneto): uint32 vec, valid SPIR-V
diff --git a/src/reader/spirv/parser_impl_test_helper.h b/src/reader/spirv/parser_impl_test_helper.h
new file mode 100644
index 0000000..3e4b8d1
--- /dev/null
+++ b/src/reader/spirv/parser_impl_test_helper.h
@@ -0,0 +1,56 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_READER_SPIRV_PARSER_IMPL_TEST_HELPER_H_
+#define SRC_READER_SPIRV_PARSER_IMPL_TEST_HELPER_H_
+
+#include <memory>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "src/context.h"
+#include "src/reader/spirv/parser_impl.h"
+
+namespace tint {
+namespace reader {
+namespace spirv {
+
+class SpvParserTest : public testing::Test {
+ public:
+  SpvParserTest() = default;
+  ~SpvParserTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::vector<uint32_t>& input) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, input);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace spirv
+}  // namespace reader
+}  // namespace tint
+
+#endif  // SRC_READER_WGSL_PARSER_IMPL_TEST_HELPER_H_
diff --git a/src/reader/spirv/parser_impl_user_name_test.cc b/src/reader/spirv/parser_impl_user_name_test.cc
index b20c021..ebe2761 100644
--- a/src/reader/spirv/parser_impl_user_name_test.cc
+++ b/src/reader/spirv/parser_impl_user_name_test.cc
@@ -17,6 +17,7 @@
 
 #include "gmock/gmock.h"
 #include "src/reader/spirv/parser_impl.h"
+#include "src/reader/spirv/parser_impl_test_helper.h"
 #include "src/reader/spirv/spirv_tools_helpers_test.h"
 
 namespace tint {
@@ -26,64 +27,62 @@
 
 using ::testing::Eq;
 
-using SpvParseUserNameTest = ::testing::Test;
-
-TEST_F(SpvParseUserNameTest, RespectOpName) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, UserName_RespectOpName) {
+  auto p = parser(test::Assemble(R"(
      OpName %1 "the_void_type"
      %1 = OpTypeVoid
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_THAT(p.namer().GetName(1), Eq("the_void_type"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_THAT(p->namer().GetName(1), Eq("the_void_type"));
 }
 
-TEST_F(SpvParseUserNameTest, DistinguishDuplicateSuggestion) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, UserName_DistinguishDuplicateSuggestion) {
+  auto p = parser(test::Assemble(R"(
      OpName %1 "vanilla"
      OpName %2 "vanilla"
      %1 = OpTypeVoid
      %2 = OpTypeInt 32 0
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_THAT(p.namer().GetName(1), Eq("vanilla"));
-  EXPECT_THAT(p.namer().GetName(2), Eq("vanilla_1"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_THAT(p->namer().GetName(1), Eq("vanilla"));
+  EXPECT_THAT(p->namer().GetName(2), Eq("vanilla_1"));
 }
 
-TEST_F(SpvParseUserNameTest, RespectOpMemberName) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, UserName_RespectOpMemberName) {
+  auto p = parser(test::Assemble(R"(
      OpMemberName %3 0 "strawberry"
      OpMemberName %3 1 "vanilla"
      OpMemberName %3 2 "chocolate"
      %2 = OpTypeInt 32 0
      %3 = OpTypeStruct %2 %2 %2
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_THAT(p.namer().GetMemberName(3, 0), Eq("strawberry"));
-  EXPECT_THAT(p.namer().GetMemberName(3, 1), Eq("vanilla"));
-  EXPECT_THAT(p.namer().GetMemberName(3, 2), Eq("chocolate"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_THAT(p->namer().GetMemberName(3, 0), Eq("strawberry"));
+  EXPECT_THAT(p->namer().GetMemberName(3, 1), Eq("vanilla"));
+  EXPECT_THAT(p->namer().GetMemberName(3, 2), Eq("chocolate"));
 }
 
-TEST_F(SpvParseUserNameTest, SynthesizeMemberNames) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, UserName_SynthesizeMemberNames) {
+  auto p = parser(test::Assemble(R"(
      %2 = OpTypeInt 32 0
      %3 = OpTypeStruct %2 %2 %2
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_THAT(p.namer().GetMemberName(3, 0), Eq("field0"));
-  EXPECT_THAT(p.namer().GetMemberName(3, 1), Eq("field1"));
-  EXPECT_THAT(p.namer().GetMemberName(3, 2), Eq("field2"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_THAT(p->namer().GetMemberName(3, 0), Eq("field0"));
+  EXPECT_THAT(p->namer().GetMemberName(3, 1), Eq("field1"));
+  EXPECT_THAT(p->namer().GetMemberName(3, 2), Eq("field2"));
 }
 
-TEST_F(SpvParseUserNameTest, MemberNamesMixUserAndSynthesized) {
-  ParserImpl p(test::Assemble(R"(
+TEST_F(SpvParserTest, UserName_MemberNamesMixUserAndSynthesized) {
+  auto p = parser(test::Assemble(R"(
      OpMemberName %3 1 "vanilla"
      %2 = OpTypeInt 32 0
      %3 = OpTypeStruct %2 %2 %2
   )"));
-  EXPECT_TRUE(p.BuildAndParseInternalModule());
-  EXPECT_THAT(p.namer().GetMemberName(3, 0), Eq("field0"));
-  EXPECT_THAT(p.namer().GetMemberName(3, 1), Eq("vanilla"));
-  EXPECT_THAT(p.namer().GetMemberName(3, 2), Eq("field2"));
+  EXPECT_TRUE(p->BuildAndParseInternalModule());
+  EXPECT_THAT(p->namer().GetMemberName(3, 0), Eq("field0"));
+  EXPECT_THAT(p->namer().GetMemberName(3, 1), Eq("vanilla"));
+  EXPECT_THAT(p->namer().GetMemberName(3, 2), Eq("field2"));
 }
 
 }  // namespace
diff --git a/src/reader/spirv/parser_test.cc b/src/reader/spirv/parser_test.cc
index 25cb34a..ea0f87d 100644
--- a/src/reader/spirv/parser_test.cc
+++ b/src/reader/spirv/parser_test.cc
@@ -18,6 +18,7 @@
 #include <vector>
 
 #include "gtest/gtest.h"
+#include "src/context.h"
 
 namespace tint {
 namespace reader {
@@ -28,7 +29,8 @@
 
 TEST_F(ParserTest, Uint32VecEmpty) {
   std::vector<uint32_t> data;
-  Parser p{data};
+  Context ctx;
+  Parser p(ctx, data);
   EXPECT_FALSE(p.Parse());
   // TODO(dneto): What message?
 }
diff --git a/src/reader/wgsl/parser.cc b/src/reader/wgsl/parser.cc
index f84dc62..597d578 100644
--- a/src/reader/wgsl/parser.cc
+++ b/src/reader/wgsl/parser.cc
@@ -20,8 +20,8 @@
 namespace reader {
 namespace wgsl {
 
-Parser::Parser(const std::string& input)
-    : Reader(), impl_(std::make_unique<ParserImpl>(input)) {}
+Parser::Parser(const Context& ctx, const std::string& input)
+    : Reader(ctx), impl_(std::make_unique<ParserImpl>(ctx, input)) {}
 
 Parser::~Parser() = default;
 
diff --git a/src/reader/wgsl/parser.h b/src/reader/wgsl/parser.h
index b3b27d9..aa511e8 100644
--- a/src/reader/wgsl/parser.h
+++ b/src/reader/wgsl/parser.h
@@ -30,8 +30,9 @@
 class Parser : public Reader {
  public:
   /// Creates a new parser
+  /// @param ctx the context object
   /// @param input the input string to parse
-  explicit Parser(const std::string& input);
+  Parser(const Context& ctx, const std::string& input);
   ~Parser() override;
 
   /// Run the parser
diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index 59d461b..eb66cd2 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -71,8 +71,8 @@
 namespace reader {
 namespace wgsl {
 
-ParserImpl::ParserImpl(const std::string& input)
-    : lexer_(std::make_unique<Lexer>(input)) {}
+ParserImpl::ParserImpl(const Context& ctx, const std::string& input)
+    : ctx_(ctx), lexer_(std::make_unique<Lexer>(input)) {}
 
 ParserImpl::~ParserImpl() = default;
 
@@ -134,6 +134,11 @@
 }
 
 bool ParserImpl::Parse() {
+  if (ctx_.type_mgr == nullptr) {
+    set_error(peek(), "missing type manager");
+    return false;
+  }
+
   translation_unit();
   return !has_error();
 }
@@ -672,8 +677,6 @@
     return nullptr;
   }
 
-  auto tm = TypeManager::Instance();
-
   auto type = type_decl();
   if (has_error())
     return nullptr;
@@ -687,14 +690,15 @@
     }
 
     str->set_name(name);
-    type = tm->Get(std::move(str));
+    type = ctx_.type_mgr->Get(std::move(str));
   }
   if (type == nullptr) {
     set_error(peek(), "invalid type for alias");
     return nullptr;
   }
 
-  auto alias = tm->Get(std::make_unique<ast::type::AliasType>(name, type));
+  auto alias =
+      ctx_.type_mgr->Get(std::make_unique<ast::type::AliasType>(name, type));
   register_alias(name, alias);
 
   return alias->AsAlias();
@@ -722,8 +726,6 @@
 //   | MAT4x3 LESS_THAN type_decl GREATER_THAN
 //   | MAT4x4 LESS_THAN type_decl GREATER_THAN
 ast::type::Type* ParserImpl::type_decl() {
-  auto tm = TypeManager::Instance();
-
   auto t = peek();
   if (t.IsIdentifier()) {
     next();  // Consume the peek
@@ -736,19 +738,19 @@
   }
   if (t.IsBool()) {
     next();  // Consume the peek
-    return tm->Get(std::make_unique<ast::type::BoolType>());
+    return ctx_.type_mgr->Get(std::make_unique<ast::type::BoolType>());
   }
   if (t.IsF32()) {
     next();  // Consume the peek
-    return tm->Get(std::make_unique<ast::type::F32Type>());
+    return ctx_.type_mgr->Get(std::make_unique<ast::type::F32Type>());
   }
   if (t.IsI32()) {
     next();  // Consume the peek
-    return tm->Get(std::make_unique<ast::type::I32Type>());
+    return ctx_.type_mgr->Get(std::make_unique<ast::type::I32Type>());
   }
   if (t.IsU32()) {
     next();  // Consume the peek
-    return tm->Get(std::make_unique<ast::type::U32Type>());
+    return ctx_.type_mgr->Get(std::make_unique<ast::type::U32Type>());
   }
   if (t.IsVec2() || t.IsVec3() || t.IsVec4()) {
     return type_decl_vector(t);
@@ -804,7 +806,7 @@
     return nullptr;
   }
 
-  return TypeManager::Instance()->Get(
+  return ctx_.type_mgr->Get(
       std::make_unique<ast::type::PointerType>(subtype, sc));
 }
 
@@ -837,7 +839,7 @@
     return nullptr;
   }
 
-  return TypeManager::Instance()->Get(
+  return ctx_.type_mgr->Get(
       std::make_unique<ast::type::VectorType>(subtype, count));
 }
 
@@ -878,7 +880,7 @@
     return nullptr;
   }
 
-  return TypeManager::Instance()->Get(
+  return ctx_.type_mgr->Get(
       std::make_unique<ast::type::ArrayType>(subtype, size));
 }
 
@@ -918,7 +920,7 @@
     return nullptr;
   }
 
-  return TypeManager::Instance()->Get(
+  return ctx_.type_mgr->Get(
       std::make_unique<ast::type::MatrixType>(subtype, rows, columns));
 }
 
@@ -1209,12 +1211,10 @@
 //   : type_decl
 //   | VOID
 ast::type::Type* ParserImpl::function_type_decl() {
-  auto tm = TypeManager::Instance();
-
   auto t = peek();
   if (t.IsVoid()) {
     next();  // Consume the peek
-    return tm->Get(std::make_unique<ast::type::VoidType>());
+    return ctx_.type_mgr->Get(std::make_unique<ast::type::VoidType>());
   }
   return type_decl();
 }
diff --git a/src/reader/wgsl/parser_impl.h b/src/reader/wgsl/parser_impl.h
index 7fa3a23..5413d85 100644
--- a/src/reader/wgsl/parser_impl.h
+++ b/src/reader/wgsl/parser_impl.h
@@ -44,6 +44,7 @@
 #include "src/ast/unless_statement.h"
 #include "src/ast/variable.h"
 #include "src/ast/variable_decoration.h"
+#include "src/context.h"
 #include "src/reader/wgsl/token.h"
 
 namespace tint {
@@ -56,8 +57,9 @@
 class ParserImpl {
  public:
   /// Creates a new parser
+  /// @param ctx the context object
   /// @param input the input string to parse
-  explicit ParserImpl(const std::string& input);
+  ParserImpl(const Context& ctx, const std::string& input);
   ~ParserImpl();
 
   /// Run the parser
@@ -349,6 +351,7 @@
   ast::type::Type* type_decl_array(Token t);
   ast::type::Type* type_decl_matrix(Token t);
 
+  const Context& ctx_;
   std::string error_;
   std::unique_ptr<Lexer> lexer_;
   std::deque<Token> token_queue_;
diff --git a/src/reader/wgsl/parser_impl_additive_expression_test.cc b/src/reader/wgsl/parser_impl_additive_expression_test.cc
index d69d61e..0b46cdb 100644
--- a/src/reader/wgsl/parser_impl_additive_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_additive_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, AdditiveExpression_Parses_Plus) {
-  ParserImpl p{"a + true"};
-  auto e = p.additive_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a + true");
+  auto e = p->additive_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,9 +47,9 @@
 }
 
 TEST_F(ParserImplTest, AdditiveExpression_Parses_Minus) {
-  ParserImpl p{"a - true"};
-  auto e = p.additive_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a - true");
+  auto e = p->additive_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -70,24 +69,24 @@
 }
 
 TEST_F(ParserImplTest, AdditiveExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} + true"};
-  auto e = p.additive_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} + true");
+  auto e = p->additive_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, AdditiveExpression_InvalidRHS) {
-  ParserImpl p{"true + if (a) {}"};
-  auto e = p.additive_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true + if (a) {}");
+  auto e = p->additive_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse right side of + expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse right side of + expression");
 }
 
 TEST_F(ParserImplTest, AdditiveExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.additive_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->additive_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_and_expression_test.cc b/src/reader/wgsl/parser_impl_and_expression_test.cc
index be1c581..262611c 100644
--- a/src/reader/wgsl/parser_impl_and_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_and_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, AndExpression_Parses) {
-  ParserImpl p{"a & true"};
-  auto e = p.and_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a & true");
+  auto e = p->and_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,24 +47,24 @@
 }
 
 TEST_F(ParserImplTest, AndExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} & true"};
-  auto e = p.and_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} & true");
+  auto e = p->and_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, AndExpression_InvalidRHS) {
-  ParserImpl p{"true & if (a) {}"};
-  auto e = p.and_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true & if (a) {}");
+  auto e = p->and_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse right side of & expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse right side of & expression");
 }
 
 TEST_F(ParserImplTest, AndExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.and_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->and_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_argument_expression_list_test.cc b/src/reader/wgsl/parser_impl_argument_expression_list_test.cc
index e053532..8b1e75a 100644
--- a/src/reader/wgsl/parser_impl_argument_expression_list_test.cc
+++ b/src/reader/wgsl/parser_impl_argument_expression_list_test.cc
@@ -21,26 +21,25 @@
 #include "src/ast/unary_method_expression.h"
 #include "src/ast/unary_op_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ArgumentExpressionList_Parses) {
-  ParserImpl p{"a"};
-  auto e = p.argument_expression_list();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a");
+  auto e = p->argument_expression_list();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
   ASSERT_EQ(e.size(), 1);
   ASSERT_TRUE(e[0]->IsIdentifier());
 }
 
 TEST_F(ParserImplTest, ArgumentExpressionList_ParsesMultiple) {
-  ParserImpl p{"a, -33, 1+2"};
-  auto e = p.argument_expression_list();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a, -33, 1+2");
+  auto e = p->argument_expression_list();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
   ASSERT_EQ(e.size(), 3);
   ASSERT_TRUE(e[0]->IsIdentifier());
@@ -49,17 +48,17 @@
 }
 
 TEST_F(ParserImplTest, ArgumentExpressionList_HandlesMissingExpression) {
-  ParserImpl p{"a, "};
-  auto e = p.argument_expression_list();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:4: unable to parse argument expression after comma");
+  auto p = parser("a, ");
+  auto e = p->argument_expression_list();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:4: unable to parse argument expression after comma");
 }
 
 TEST_F(ParserImplTest, ArgumentExpressionList_HandlesInvalidExpression) {
-  ParserImpl p{"if(a) {}"};
-  auto e = p.argument_expression_list();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:1: unable to parse argument expression");
+  auto p = parser("if(a) {}");
+  auto e = p->argument_expression_list();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:1: unable to parse argument expression");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_assignment_stmt_test.cc b/src/reader/wgsl/parser_impl_assignment_stmt_test.cc
index 9de59f3..45f6cdd 100644
--- a/src/reader/wgsl/parser_impl_assignment_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_assignment_stmt_test.cc
@@ -21,17 +21,16 @@
 #include "src/ast/literal.h"
 #include "src/ast/member_accessor_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, AssignmentStmt_Parses_ToVariable) {
-  ParserImpl p{"a = 123"};
-  auto e = p.assignment_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a = 123");
+  auto e = p->assignment_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsAssign());
@@ -53,9 +52,9 @@
 }
 
 TEST_F(ParserImplTest, AssignmentStmt_Parses_ToMember) {
-  ParserImpl p{"a.b.c[2].d = 123"};
-  auto e = p.assignment_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a.b.c[2].d = 123");
+  auto e = p->assignment_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsAssign());
@@ -109,26 +108,26 @@
 }
 
 TEST_F(ParserImplTest, AssignmentStmt_MissingEqual) {
-  ParserImpl p{"a.b.c[2].d 123"};
-  auto e = p.assignment_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a.b.c[2].d 123");
+  auto e = p->assignment_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: missing = for assignment");
+  EXPECT_EQ(p->error(), "1:12: missing = for assignment");
 }
 
 TEST_F(ParserImplTest, AssignmentStmt_InvalidLHS) {
-  ParserImpl p{"if (true) {} = 123"};
-  auto e = p.assignment_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (true) {} = 123");
+  auto e = p->assignment_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, AssignmentStmt_InvalidRHS) {
-  ParserImpl p{"a.b.c[2].d = if (true) {}"};
-  auto e = p.assignment_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a.b.c[2].d = if (true) {}");
+  auto e = p->assignment_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: unable to parse right side of assignment");
+  EXPECT_EQ(p->error(), "1:14: unable to parse right side of assignment");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_body_stmt_test.cc b/src/reader/wgsl/parser_impl_body_stmt_test.cc
index 6f57a60..fb1e635 100644
--- a/src/reader/wgsl/parser_impl_body_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_body_stmt_test.cc
@@ -14,21 +14,20 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, BodyStmt) {
-  ParserImpl p{R"({
+  auto p = parser(R"({
   kill;
   nop;
   return 1 + b / 2;
-})"};
-  auto e = p.body_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+})");
+  auto e = p->body_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 3);
   EXPECT_TRUE(e[0]->IsKill());
   EXPECT_TRUE(e[1]->IsNop());
@@ -36,24 +35,24 @@
 }
 
 TEST_F(ParserImplTest, BodyStmt_Empty) {
-  ParserImpl p{"{}"};
-  auto e = p.body_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("{}");
+  auto e = p->body_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_EQ(e.size(), 0);
 }
 
 TEST_F(ParserImplTest, BodyStmt_InvalidStmt) {
-  ParserImpl p{"{fn main() -> void {}}"};
-  auto e = p.body_stmt();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:2: missing }");
+  auto p = parser("{fn main() -> void {}}");
+  auto e = p->body_stmt();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:2: missing }");
 }
 
 TEST_F(ParserImplTest, BodyStmt_MissingRightParen) {
-  ParserImpl p{"{return;"};
-  auto e = p.body_stmt();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:9: missing }");
+  auto p = parser("{return;");
+  auto e = p->body_stmt();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:9: missing }");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_break_stmt_test.cc b/src/reader/wgsl/parser_impl_break_stmt_test.cc
index 932871e..bb1f67b 100644
--- a/src/reader/wgsl/parser_impl_break_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_break_stmt_test.cc
@@ -17,17 +17,16 @@
 #include "src/ast/return_statement.h"
 #include "src/ast/statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, BreakStmt) {
-  ParserImpl p{"break"};
-  auto e = p.break_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("break");
+  auto e = p->break_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsBreak());
   EXPECT_EQ(e->condition(), ast::StatementCondition::kNone);
@@ -35,9 +34,9 @@
 }
 
 TEST_F(ParserImplTest, BreakStmt_WithIf) {
-  ParserImpl p{"break if (a == b)"};
-  auto e = p.break_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("break if (a == b)");
+  auto e = p->break_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsBreak());
   EXPECT_EQ(e->condition(), ast::StatementCondition::kIf);
@@ -46,9 +45,9 @@
 }
 
 TEST_F(ParserImplTest, BreakStmt_WithUnless) {
-  ParserImpl p{"break unless (a == b)"};
-  auto e = p.break_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("break unless (a == b)");
+  auto e = p->break_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsBreak());
   EXPECT_EQ(e->condition(), ast::StatementCondition::kUnless);
@@ -57,19 +56,19 @@
 }
 
 TEST_F(ParserImplTest, BreakStmt_InvalidRHS) {
-  ParserImpl p{"break if (a = b)"};
-  auto e = p.break_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("break if (a = b)");
+  auto e = p->break_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: expected )");
+  EXPECT_EQ(p->error(), "1:13: expected )");
 }
 
 TEST_F(ParserImplTest, BreakStmt_MissingRHS) {
-  ParserImpl p{"break if"};
-  auto e = p.break_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("break if");
+  auto e = p->break_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: expected (");
+  EXPECT_EQ(p->error(), "1:9: expected (");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_builtin_decoration_test.cc b/src/reader/wgsl/parser_impl_builtin_decoration_test.cc
index 4b5edf1..dbb2f46 100644
--- a/src/reader/wgsl/parser_impl_builtin_decoration_test.cc
+++ b/src/reader/wgsl/parser_impl_builtin_decoration_test.cc
@@ -15,12 +15,12 @@
 #include "gtest/gtest.h"
 #include "src/ast/builtin.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
-
-using ParserImplTest = testing::Test;
+namespace {
 
 struct BuiltinData {
   const char* input;
@@ -30,16 +30,41 @@
   out << std::string(data.input);
   return out;
 }
-using BuiltinTest = testing::TestWithParam<BuiltinData>;
+
+class BuiltinTest : public testing::TestWithParam<BuiltinData> {
+ public:
+  BuiltinTest() = default;
+  ~BuiltinTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace
+
 TEST_P(BuiltinTest, Parses) {
   auto params = GetParam();
-  ParserImpl p{params.input};
+  auto p = parser(params.input);
 
-  auto builtin = p.builtin_decoration();
-  ASSERT_FALSE(p.has_error());
+  auto builtin = p->builtin_decoration();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(builtin, params.result);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsEof());
 }
 INSTANTIATE_TEST_SUITE_P(
@@ -60,11 +85,11 @@
                     ast::Builtin::kGlobalInvocationId}));
 
 TEST_F(ParserImplTest, BuiltinDecoration_NoMatch) {
-  ParserImpl p{"not-a-builtin"};
-  auto builtin = p.builtin_decoration();
+  auto p = parser("not-a-builtin");
+  auto builtin = p->builtin_decoration();
   ASSERT_EQ(builtin, ast::Builtin::kNone);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsIdentifier());
   EXPECT_EQ(t.to_str(), "not");
 }
diff --git a/src/reader/wgsl/parser_impl_case_body_test.cc b/src/reader/wgsl/parser_impl_case_body_test.cc
index 621a8a4..56632ed 100644
--- a/src/reader/wgsl/parser_impl_case_body_test.cc
+++ b/src/reader/wgsl/parser_impl_case_body_test.cc
@@ -14,54 +14,53 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, CaseBody_Empty) {
-  ParserImpl p{""};
-  auto e = p.case_body();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("");
+  auto e = p->case_body();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_EQ(e.size(), 0);
 }
 
 TEST_F(ParserImplTest, CaseBody_Statements) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
   var a: i32;
-  a = 2;)"};
+  a = 2;)");
 
-  auto e = p.case_body();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto e = p->case_body();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 2);
   EXPECT_TRUE(e[0]->IsVariable());
   EXPECT_TRUE(e[1]->IsAssign());
 }
 
 TEST_F(ParserImplTest, CaseBody_InvalidStatement) {
-  ParserImpl p{"a ="};
-  auto e = p.case_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a =");
+  auto e = p->case_body();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(e.size(), 0);
-  EXPECT_EQ(p.error(), "1:4: unable to parse right side of assignment");
+  EXPECT_EQ(p->error(), "1:4: unable to parse right side of assignment");
 }
 
 TEST_F(ParserImplTest, CaseBody_Fallthrough) {
-  ParserImpl p{"fallthrough;"};
-  auto e = p.case_body();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("fallthrough;");
+  auto e = p->case_body();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 1);
   EXPECT_TRUE(e[0]->IsFallthrough());
 }
 
 TEST_F(ParserImplTest, CaseBody_Fallthrough_MissingSemicolon) {
-  ParserImpl p{"fallthrough"};
-  auto e = p.case_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fallthrough");
+  auto e = p->case_body();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(e.size(), 0);
-  EXPECT_EQ(p.error(), "1:12: missing ;");
+  EXPECT_EQ(p->error(), "1:12: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_const_expr_test.cc b/src/reader/wgsl/parser_impl_const_expr_test.cc
index ffdb348..cf4dad9 100644
--- a/src/reader/wgsl/parser_impl_const_expr_test.cc
+++ b/src/reader/wgsl/parser_impl_const_expr_test.cc
@@ -19,17 +19,16 @@
 #include "src/ast/type/vector_type.h"
 #include "src/ast/type_initializer_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ConstExpr_TypeDecl) {
-  ParserImpl p{"vec2<f32>(1., 2.)"};
-  auto e = p.const_expr();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("vec2<f32>(1., 2.)");
+  auto e = p->const_expr();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsInitializer());
   ASSERT_TRUE(e->AsInitializer()->IsTypeInitializer());
@@ -55,57 +54,57 @@
 }
 
 TEST_F(ParserImplTest, ConstExpr_TypeDecl_MissingRightParen) {
-  ParserImpl p{"vec2<f32>(1., 2."};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<f32>(1., 2.");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:17: missing ) for type initializer");
+  EXPECT_EQ(p->error(), "1:17: missing ) for type initializer");
 }
 
 TEST_F(ParserImplTest, ConstExpr_TypeDecl_MissingLeftParen) {
-  ParserImpl p{"vec2<f32> 1., 2.)"};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<f32> 1., 2.)");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing ( for type initializer");
+  EXPECT_EQ(p->error(), "1:11: missing ( for type initializer");
 }
 
 TEST_F(ParserImplTest, ConstExpr_TypeDecl_HangingComma) {
-  ParserImpl p{"vec2<f32>(1.,)"};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<f32>(1.,)");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: unable to parse const literal");
+  EXPECT_EQ(p->error(), "1:14: unable to parse const literal");
 }
 
 TEST_F(ParserImplTest, ConstExpr_TypeDecl_MissingComma) {
-  ParserImpl p{"vec2<f32>(1. 2."};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<f32>(1. 2.");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing ) for type initializer");
+  EXPECT_EQ(p->error(), "1:14: missing ) for type initializer");
 }
 
 TEST_F(ParserImplTest, ConstExpr_MissingExpr) {
-  ParserImpl p{"vec2<f32>()"};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<f32>()");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: unable to parse const literal");
+  EXPECT_EQ(p->error(), "1:11: unable to parse const literal");
 }
 
 TEST_F(ParserImplTest, ConstExpr_InvalidExpr) {
-  ParserImpl p{"vec2<f32>(1., if(a) {})"};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<f32>(1., if(a) {})");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: unable to parse const literal");
+  EXPECT_EQ(p->error(), "1:15: unable to parse const literal");
 }
 
 TEST_F(ParserImplTest, ConstExpr_ConstLiteral) {
-  ParserImpl p{"true"};
-  auto e = p.const_expr();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("true");
+  auto e = p->const_expr();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsInitializer());
   ASSERT_TRUE(e->AsInitializer()->IsConstInitializer());
@@ -115,11 +114,11 @@
 }
 
 TEST_F(ParserImplTest, ConstExpr_ConstLiteral_Invalid) {
-  ParserImpl p{"invalid"};
-  auto e = p.const_expr();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("invalid");
+  auto e = p->const_expr();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:1: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:1: unknown type alias 'invalid'");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_const_literal_test.cc b/src/reader/wgsl/parser_impl_const_literal_test.cc
index f9572ea..aa5989e 100644
--- a/src/reader/wgsl/parser_impl_const_literal_test.cc
+++ b/src/reader/wgsl/parser_impl_const_literal_test.cc
@@ -18,68 +18,67 @@
 #include "src/ast/int_literal.h"
 #include "src/ast/uint_literal.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ConstLiteral_Int) {
-  ParserImpl p{"-234"};
-  auto c = p.const_literal();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("-234");
+  auto c = p->const_literal();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(c, nullptr);
   ASSERT_TRUE(c->IsInt());
   EXPECT_EQ(c->AsInt()->value(), -234);
 }
 
 TEST_F(ParserImplTest, ConstLiteral_Uint) {
-  ParserImpl p{"234u"};
-  auto c = p.const_literal();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("234u");
+  auto c = p->const_literal();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(c, nullptr);
   ASSERT_TRUE(c->IsUint());
   EXPECT_EQ(c->AsUint()->value(), 234u);
 }
 
 TEST_F(ParserImplTest, ConstLiteral_Float) {
-  ParserImpl p{"234.e12"};
-  auto c = p.const_literal();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("234.e12");
+  auto c = p->const_literal();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(c, nullptr);
   ASSERT_TRUE(c->IsFloat());
   EXPECT_FLOAT_EQ(c->AsFloat()->value(), 234e12);
 }
 
 TEST_F(ParserImplTest, ConstLiteral_InvalidFloat) {
-  ParserImpl p{"1.2e+256"};
-  auto c = p.const_literal();
+  auto p = parser("1.2e+256");
+  auto c = p->const_literal();
   ASSERT_EQ(c, nullptr);
 }
 
 TEST_F(ParserImplTest, ConstLiteral_True) {
-  ParserImpl p{"true"};
-  auto c = p.const_literal();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("true");
+  auto c = p->const_literal();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(c, nullptr);
   ASSERT_TRUE(c->IsBool());
   EXPECT_TRUE(c->AsBool()->IsTrue());
 }
 
 TEST_F(ParserImplTest, ConstLiteral_False) {
-  ParserImpl p{"false"};
-  auto c = p.const_literal();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("false");
+  auto c = p->const_literal();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(c, nullptr);
   ASSERT_TRUE(c->IsBool());
   EXPECT_TRUE(c->AsBool()->IsFalse());
 }
 
 TEST_F(ParserImplTest, ConstLiteral_NoMatch) {
-  ParserImpl p{"another-token"};
-  auto c = p.const_literal();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("another-token");
+  auto c = p->const_literal();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(c, nullptr);
 }
 
diff --git a/src/reader/wgsl/parser_impl_continue_stmt_test.cc b/src/reader/wgsl/parser_impl_continue_stmt_test.cc
index 335cdf2..ebcca06 100644
--- a/src/reader/wgsl/parser_impl_continue_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_continue_stmt_test.cc
@@ -17,17 +17,16 @@
 #include "src/ast/return_statement.h"
 #include "src/ast/statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ContinueStmt) {
-  ParserImpl p{"continue"};
-  auto e = p.continue_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("continue");
+  auto e = p->continue_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsContinue());
   EXPECT_EQ(e->condition(), ast::StatementCondition::kNone);
@@ -35,9 +34,9 @@
 }
 
 TEST_F(ParserImplTest, ContinueStmt_WithIf) {
-  ParserImpl p{"continue if (a == b)"};
-  auto e = p.continue_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("continue if (a == b)");
+  auto e = p->continue_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsContinue());
   EXPECT_EQ(e->condition(), ast::StatementCondition::kIf);
@@ -46,9 +45,9 @@
 }
 
 TEST_F(ParserImplTest, ContinueStmt_WithUnless) {
-  ParserImpl p{"continue unless (a == b)"};
-  auto e = p.continue_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("continue unless (a == b)");
+  auto e = p->continue_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsContinue());
   EXPECT_EQ(e->condition(), ast::StatementCondition::kUnless);
@@ -57,19 +56,19 @@
 }
 
 TEST_F(ParserImplTest, ContinueStmt_InvalidRHS) {
-  ParserImpl p{"continue if (a = b)"};
-  auto e = p.continue_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("continue if (a = b)");
+  auto e = p->continue_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:16: expected )");
+  EXPECT_EQ(p->error(), "1:16: expected )");
 }
 
 TEST_F(ParserImplTest, ContinueStmt_MissingRHS) {
-  ParserImpl p{"continue if"};
-  auto e = p.continue_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("continue if");
+  auto e = p->continue_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: expected (");
+  EXPECT_EQ(p->error(), "1:12: expected (");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_continuing_stmt_test.cc b/src/reader/wgsl/parser_impl_continuing_stmt_test.cc
index 93b79c0..650e4ea 100644
--- a/src/reader/wgsl/parser_impl_continuing_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_continuing_stmt_test.cc
@@ -14,27 +14,26 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ContinuingStmt) {
-  ParserImpl p{"continuing { nop; }"};
-  auto e = p.continuing_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("continuing { nop; }");
+  auto e = p->continuing_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 1);
   ASSERT_TRUE(e[0]->IsNop());
 }
 
 TEST_F(ParserImplTest, ContinuingStmt_InvalidBody) {
-  ParserImpl p{"continuing { nop }"};
-  auto e = p.continuing_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("continuing { nop }");
+  auto e = p->continuing_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e.size(), 0);
-  EXPECT_EQ(p.error(), "1:18: missing ;");
+  EXPECT_EQ(p->error(), "1:18: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_derivative_modifier_test.cc b/src/reader/wgsl/parser_impl_derivative_modifier_test.cc
index 4c471d2..9732216 100644
--- a/src/reader/wgsl/parser_impl_derivative_modifier_test.cc
+++ b/src/reader/wgsl/parser_impl_derivative_modifier_test.cc
@@ -15,12 +15,12 @@
 #include "gtest/gtest.h"
 #include "src/ast/derivative_modifier.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
-
-using ParserImplTest = testing::Test;
+namespace {
 
 struct DerivativeModifierData {
   const char* input;
@@ -31,16 +31,42 @@
   out << std::string(data.input);
   return out;
 }
-using DerivativeModifierTest = testing::TestWithParam<DerivativeModifierData>;
+
+class DerivativeModifierTest
+    : public testing::TestWithParam<DerivativeModifierData> {
+ public:
+  DerivativeModifierTest() = default;
+  ~DerivativeModifierTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace
+
 TEST_P(DerivativeModifierTest, Parses) {
   auto params = GetParam();
-  ParserImpl p{params.input};
+  auto p = parser(params.input);
 
-  auto mod = p.derivative_modifier();
-  ASSERT_FALSE(p.has_error());
+  auto mod = p->derivative_modifier();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(mod, params.result);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsEof());
 }
 INSTANTIATE_TEST_SUITE_P(
@@ -51,11 +77,11 @@
         DerivativeModifierData{"coarse", ast::DerivativeModifier::kCoarse}));
 
 TEST_F(ParserImplTest, DerivativeModifier_NoMatch) {
-  ParserImpl p{"not-a-modifier"};
-  auto stage = p.derivative_modifier();
+  auto p = parser("not-a-modifier");
+  auto stage = p->derivative_modifier();
   ASSERT_EQ(stage, ast::DerivativeModifier::kNone);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsIdentifier());
   EXPECT_EQ(t.to_str(), "not");
 }
diff --git a/src/reader/wgsl/parser_impl_else_stmt_test.cc b/src/reader/wgsl/parser_impl_else_stmt_test.cc
index cbfeff6..a83eec3 100644
--- a/src/reader/wgsl/parser_impl_else_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_else_stmt_test.cc
@@ -15,17 +15,16 @@
 #include "gtest/gtest.h"
 #include "src/ast/else_statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ElseStmt) {
-  ParserImpl p{"else { a = b; c = d; }"};
-  auto e = p.else_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("else { a = b; c = d; }");
+  auto e = p->else_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsElse());
   ASSERT_EQ(e->condition(), nullptr);
@@ -33,19 +32,19 @@
 }
 
 TEST_F(ParserImplTest, ElseStmt_InvalidBody) {
-  ParserImpl p{"else { fn main() -> void {}}"};
-  auto e = p.else_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("else { fn main() -> void {}}");
+  auto e = p->else_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing }");
+  EXPECT_EQ(p->error(), "1:8: missing }");
 }
 
 TEST_F(ParserImplTest, ElseStmt_MissingBody) {
-  ParserImpl p{"else"};
-  auto e = p.else_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("else");
+  auto e = p->else_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing {");
+  EXPECT_EQ(p->error(), "1:5: missing {");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_elseif_stmt_test.cc b/src/reader/wgsl/parser_impl_elseif_stmt_test.cc
index b597fed..e554610 100644
--- a/src/reader/wgsl/parser_impl_elseif_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_elseif_stmt_test.cc
@@ -15,17 +15,16 @@
 #include "gtest/gtest.h"
 #include "src/ast/else_statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ElseIfStmt) {
-  ParserImpl p{"elseif (a == 4) { a = b; c = d; }"};
-  auto e = p.elseif_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("elseif (a == 4) { a = b; c = d; }");
+  auto e = p->elseif_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 1);
 
   ASSERT_TRUE(e[0]->IsElse());
@@ -35,9 +34,9 @@
 }
 
 TEST_F(ParserImplTest, ElseIfStmt_Multiple) {
-  ParserImpl p{"elseif (a == 4) { a = b; c = d; } elseif(c) { d = 2; }"};
-  auto e = p.elseif_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("elseif (a == 4) { a = b; c = d; } elseif(c) { d = 2; }");
+  auto e = p->elseif_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 2);
 
   ASSERT_TRUE(e[0]->IsElse());
@@ -52,17 +51,17 @@
 }
 
 TEST_F(ParserImplTest, ElseIfStmt_InvalidBody) {
-  ParserImpl p{"elseif (true) { fn main() -> void {}}"};
-  auto e = p.elseif_stmt();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:17: missing }");
+  auto p = parser("elseif (true) { fn main() -> void {}}");
+  auto e = p->elseif_stmt();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:17: missing }");
 }
 
 TEST_F(ParserImplTest, ElseIfStmt_MissingBody) {
-  ParserImpl p{"elseif (true)"};
-  auto e = p.elseif_stmt();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:14: missing {");
+  auto p = parser("elseif (true)");
+  auto e = p->elseif_stmt();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:14: missing {");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_entry_point_decl_test.cc b/src/reader/wgsl/parser_impl_entry_point_decl_test.cc
index 3afdc90..2266777 100644
--- a/src/reader/wgsl/parser_impl_entry_point_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_entry_point_decl_test.cc
@@ -15,105 +15,104 @@
 #include "gtest/gtest.h"
 #include "src/ast/variable.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, EntryPoint_Parses) {
-  ParserImpl p{"entry_point fragment = main"};
-  auto e = p.entry_point_decl();
+  auto p = parser("entry_point fragment = main");
+  auto e = p->entry_point_decl();
   ASSERT_NE(e, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(e->stage(), ast::PipelineStage::kFragment);
   EXPECT_EQ(e->name(), "main");
   EXPECT_EQ(e->function_name(), "main");
 }
 
 TEST_F(ParserImplTest, EntryPoint_ParsesWithStringName) {
-  ParserImpl p{R"(entry_point vertex as "main" = vtx_main)"};
-  auto e = p.entry_point_decl();
+  auto p = parser(R"(entry_point vertex as "main" = vtx_main)");
+  auto e = p->entry_point_decl();
   ASSERT_NE(e, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(e->stage(), ast::PipelineStage::kVertex);
   EXPECT_EQ(e->name(), "main");
   EXPECT_EQ(e->function_name(), "vtx_main");
 }
 
 TEST_F(ParserImplTest, EntryPoint_ParsesWithIdentName) {
-  ParserImpl p{R"(entry_point vertex as main = vtx_main)"};
-  auto e = p.entry_point_decl();
+  auto p = parser(R"(entry_point vertex as main = vtx_main)");
+  auto e = p->entry_point_decl();
   ASSERT_NE(e, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(e->stage(), ast::PipelineStage::kVertex);
   EXPECT_EQ(e->name(), "main");
   EXPECT_EQ(e->function_name(), "vtx_main");
 }
 
 TEST_F(ParserImplTest, EntryPoint_MissingFnName) {
-  ParserImpl p{R"(entry_point vertex as main =)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point vertex as main =)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:29: invalid function name for entry point");
+  EXPECT_EQ(p->error(), "1:29: invalid function name for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_InvalidFnName) {
-  ParserImpl p{R"(entry_point vertex as main = 123)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point vertex as main = 123)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:30: invalid function name for entry point");
+  EXPECT_EQ(p->error(), "1:30: invalid function name for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_MissingEqual) {
-  ParserImpl p{R"(entry_point vertex as main vtx_main)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point vertex as main vtx_main)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:28: missing = for entry point");
+  EXPECT_EQ(p->error(), "1:28: missing = for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_MissingName) {
-  ParserImpl p{R"(entry_point vertex as = vtx_main)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point vertex as = vtx_main)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:23: invalid name for entry point");
+  EXPECT_EQ(p->error(), "1:23: invalid name for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_InvalidName) {
-  ParserImpl p{R"(entry_point vertex as 123 = vtx_main)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point vertex as 123 = vtx_main)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:23: invalid name for entry point");
+  EXPECT_EQ(p->error(), "1:23: invalid name for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_MissingStageWithIdent) {
-  ParserImpl p{R"(entry_point as 123 = vtx_main)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point as 123 = vtx_main)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing pipeline stage for entry point");
+  EXPECT_EQ(p->error(), "1:13: missing pipeline stage for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_MissingStage) {
-  ParserImpl p{R"(entry_point = vtx_main)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point = vtx_main)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing pipeline stage for entry point");
+  EXPECT_EQ(p->error(), "1:13: missing pipeline stage for entry point");
 }
 
 TEST_F(ParserImplTest, EntryPoint_InvalidStage) {
-  ParserImpl p{R"(entry_point invalid = vtx_main)"};
-  auto e = p.entry_point_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser(R"(entry_point invalid = vtx_main)");
+  auto e = p->entry_point_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing pipeline stage for entry point");
+  EXPECT_EQ(p->error(), "1:13: missing pipeline stage for entry point");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_equality_expression_test.cc b/src/reader/wgsl/parser_impl_equality_expression_test.cc
index 73a3922..9dbc269 100644
--- a/src/reader/wgsl/parser_impl_equality_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_equality_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, EqualityExpression_Parses_Equal) {
-  ParserImpl p{"a == true"};
-  auto e = p.equality_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a == true");
+  auto e = p->equality_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,9 +47,9 @@
 }
 
 TEST_F(ParserImplTest, EqualityExpression_Parses_NotEqual) {
-  ParserImpl p{"a != true"};
-  auto e = p.equality_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a != true");
+  auto e = p->equality_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -70,24 +69,24 @@
 }
 
 TEST_F(ParserImplTest, EqualityExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} == true"};
-  auto e = p.equality_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} == true");
+  auto e = p->equality_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, EqualityExpression_InvalidRHS) {
-  ParserImpl p{"true == if (a) {}"};
-  auto e = p.equality_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true == if (a) {}");
+  auto e = p->equality_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse right side of == expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse right side of == expression");
 }
 
 TEST_F(ParserImplTest, EqualityExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.equality_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->equality_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_exclusive_or_expression_test.cc b/src/reader/wgsl/parser_impl_exclusive_or_expression_test.cc
index dfc7af9..34f0cd6 100644
--- a/src/reader/wgsl/parser_impl_exclusive_or_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_exclusive_or_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ExclusiveOrExpression_Parses) {
-  ParserImpl p{"a ^ true"};
-  auto e = p.exclusive_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a ^ true");
+  auto e = p->exclusive_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,24 +47,24 @@
 }
 
 TEST_F(ParserImplTest, ExclusiveOrExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} ^ true"};
-  auto e = p.exclusive_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} ^ true");
+  auto e = p->exclusive_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, ExclusiveOrExpression_InvalidRHS) {
-  ParserImpl p{"true ^ if (a) {}"};
-  auto e = p.exclusive_or_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true ^ if (a) {}");
+  auto e = p->exclusive_or_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse right side of ^ expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse right side of ^ expression");
 }
 
 TEST_F(ParserImplTest, ExclusiveOrExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.exclusive_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->exclusive_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_function_decl_test.cc b/src/reader/wgsl/parser_impl_function_decl_test.cc
index 869e3d5..da430fc 100644
--- a/src/reader/wgsl/parser_impl_function_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_function_decl_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/function.h"
 #include "src/ast/type/type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, FunctionDecl) {
-  ParserImpl p{"fn main(a : i32, b : f32) -> void { return; }"};
-  auto f = p.function_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("fn main(a : i32, b : f32) -> void { return; }");
+  auto f = p->function_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(f, nullptr);
 
   EXPECT_EQ(f->name(), "main");
@@ -45,19 +44,19 @@
 }
 
 TEST_F(ParserImplTest, FunctionDecl_InvalidHeader) {
-  ParserImpl p{"fn main() -> { }"};
-  auto f = p.function_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main() -> { }");
+  auto f = p->function_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:14: unable to determine function return type");
+  EXPECT_EQ(p->error(), "1:14: unable to determine function return type");
 }
 
 TEST_F(ParserImplTest, FunctionDecl_InvalidBody) {
-  ParserImpl p{"fn main() -> void { return }"};
-  auto f = p.function_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main() -> void { return }");
+  auto f = p->function_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:28: missing ;");
+  EXPECT_EQ(p->error(), "1:28: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_function_header_test.cc b/src/reader/wgsl/parser_impl_function_header_test.cc
index 1ac9bc6..b412b25 100644
--- a/src/reader/wgsl/parser_impl_function_header_test.cc
+++ b/src/reader/wgsl/parser_impl_function_header_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/function.h"
 #include "src/ast/type/type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, FunctionHeader) {
-  ParserImpl p{"fn main(a : i32, b: f32) -> void"};
-  auto f = p.function_header();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("fn main(a : i32, b: f32) -> void");
+  auto f = p->function_header();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(f, nullptr);
 
   EXPECT_EQ(f->name(), "main");
@@ -37,67 +36,67 @@
 }
 
 TEST_F(ParserImplTest, FunctionHeader_MissingIdent) {
-  ParserImpl p{"fn () ->"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn () ->");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:4: missing identifier for function");
+  EXPECT_EQ(p->error(), "1:4: missing identifier for function");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_InvalidIdent) {
-  ParserImpl p{"fn 133main() -> i32"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn 133main() -> i32");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:4: missing identifier for function");
+  EXPECT_EQ(p->error(), "1:4: missing identifier for function");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_MissingParenLeft) {
-  ParserImpl p{"fn main) -> i32"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main) -> i32");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ( for function declaration");
+  EXPECT_EQ(p->error(), "1:8: missing ( for function declaration");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_InvalidParamList) {
-  ParserImpl p{"fn main(a :i32,) -> i32"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main(a :i32,) -> i32");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:15: found , but no variable declaration");
+  EXPECT_EQ(p->error(), "1:15: found , but no variable declaration");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_MissingParenRight) {
-  ParserImpl p{"fn main( -> i32"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main( -> i32");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:10: missing ) for function declaration");
+  EXPECT_EQ(p->error(), "1:10: missing ) for function declaration");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_MissingArrow) {
-  ParserImpl p{"fn main() i32"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main() i32");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing -> for function declaration");
+  EXPECT_EQ(p->error(), "1:11: missing -> for function declaration");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_InvalidReturnType) {
-  ParserImpl p{"fn main() -> invalid"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main() -> invalid");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:14: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:14: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, FunctionHeader_MissingReturnType) {
-  ParserImpl p{"fn main() ->"};
-  auto f = p.function_header();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fn main() ->");
+  auto f = p->function_header();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(f, nullptr);
-  EXPECT_EQ(p.error(), "1:13: unable to determine function return type");
+  EXPECT_EQ(p->error(), "1:13: unable to determine function return type");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_function_type_decl_test.cc b/src/reader/wgsl/parser_impl_function_type_decl_test.cc
index 59e17bc..5f15068 100644
--- a/src/reader/wgsl/parser_impl_function_type_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_function_type_decl_test.cc
@@ -19,45 +19,38 @@
 #include "src/ast/type/vector_type.h"
 #include "src/ast/type/void_type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, FunctionTypeDecl_Void) {
-  auto tm = TypeManager::Instance();
-  auto v = tm->Get(std::make_unique<ast::type::VoidType>());
+  auto v = tm()->Get(std::make_unique<ast::type::VoidType>());
 
-  ParserImpl p{"void"};
-  auto e = p.function_type_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("void");
+  auto e = p->function_type_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, v);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, FunctionTypeDecl_Type) {
-  auto tm = TypeManager::Instance();
-  auto f32 = tm->Get(std::make_unique<ast::type::F32Type>());
-  auto vec2 = tm->Get(std::make_unique<ast::type::VectorType>(f32, 2));
+  auto f32 = tm()->Get(std::make_unique<ast::type::F32Type>());
+  auto vec2 = tm()->Get(std::make_unique<ast::type::VectorType>(f32, 2));
 
-  ParserImpl p{"vec2<f32>"};
-  auto e = p.function_type_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("vec2<f32>");
+  auto e = p->function_type_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, vec2);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, FunctionTypeDecl_InvalidType) {
-  ParserImpl p{"vec2<invalid>"};
-  auto e = p.function_type_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec2<invalid>");
+  auto e = p->function_type_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:6: unknown type alias 'invalid'");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_global_constant_decl_test.cc b/src/reader/wgsl/parser_impl_global_constant_decl_test.cc
index 5f9768b..32789bb 100644
--- a/src/reader/wgsl/parser_impl_global_constant_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_global_constant_decl_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/decorated_variable.h"
 #include "src/ast/variable_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, GlobalConstantDecl) {
-  ParserImpl p{"const a : f32 = 1."};
-  auto e = p.global_constant_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("const a : f32 = 1.");
+  auto e = p->global_constant_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   EXPECT_TRUE(e->is_const());
@@ -39,35 +38,35 @@
 }
 
 TEST_F(ParserImplTest, GlobalConstantDecl_MissingEqual) {
-  ParserImpl p{"const a: f32 1."};
-  auto e = p.global_constant_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a: f32 1.");
+  auto e = p->global_constant_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing = for const declaration");
+  EXPECT_EQ(p->error(), "1:14: missing = for const declaration");
 }
 
 TEST_F(ParserImplTest, GlobalConstantDecl_InvalidVariable) {
-  ParserImpl p{"const a: invalid = 1."};
-  auto e = p.global_constant_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a: invalid = 1.");
+  auto e = p->global_constant_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:10: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, GlobalConstantDecl_InvalidExpression) {
-  ParserImpl p{"const a: f32 = if (a) {}"};
-  auto e = p.global_constant_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a: f32 = if (a) {}");
+  auto e = p->global_constant_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:16: unable to parse const literal");
+  EXPECT_EQ(p->error(), "1:16: unable to parse const literal");
 }
 
 TEST_F(ParserImplTest, GlobalConstantDecl_MissingExpression) {
-  ParserImpl p{"const a: f32 ="};
-  auto e = p.global_constant_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a: f32 =");
+  auto e = p->global_constant_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: unable to parse const literal");
+  EXPECT_EQ(p->error(), "1:15: unable to parse const literal");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_global_decl_test.cc b/src/reader/wgsl/parser_impl_global_decl_test.cc
index 86c22a7..3cb4eb5 100644
--- a/src/reader/wgsl/parser_impl_global_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_global_decl_test.cc
@@ -14,25 +14,24 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, GlobalDecl_Semicolon) {
-  ParserImpl p(";");
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser(";");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 }
 
 TEST_F(ParserImplTest, GlobalDecl_Import) {
-  ParserImpl p{R"(import "GLSL.std.430" as glsl;)"};
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser(R"(import "GLSL.std.430" as glsl;)");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(1, m.imports().size());
 
   const auto& import = m.imports()[0];
@@ -41,27 +40,27 @@
 }
 
 TEST_F(ParserImplTest, GlobalDecl_Import_Invalid) {
-  ParserImpl p{R"(import as glsl;)"};
-  p.global_decl();
+  auto p = parser(R"(import as glsl;)");
+  p->global_decl();
 
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: missing path for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: missing path for import");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_Import_Invalid_MissingSemicolon) {
-  ParserImpl p{R"(import "GLSL.std.430" as glsl)"};
-  p.global_decl();
+  auto p = parser(R"(import "GLSL.std.430" as glsl)");
+  p->global_decl();
 
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:30: missing ';' for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:30: missing ';' for import");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_GlobalVariable) {
-  ParserImpl p{"var<out> a : vec2<i32> = vec2<i32>(1, 2);"};
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("var<out> a : vec2<i32> = vec2<i32>(1, 2);");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(m.global_variables().size(), 1);
 
   auto v = m.global_variables()[0].get();
@@ -69,25 +68,25 @@
 }
 
 TEST_F(ParserImplTest, GlobalDecl_GlobalVariable_Invalid) {
-  ParserImpl p{"var<out> a : vec2<invalid>;"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:19: unknown type alias 'invalid'");
+  auto p = parser("var<out> a : vec2<invalid>;");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:19: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_GlobalVariable_MissingSemicolon) {
-  ParserImpl p{"var<out> a : vec2<i32>"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:23: missing ';' for variable declaration");
+  auto p = parser("var<out> a : vec2<i32>");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:23: missing ';' for variable declaration");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_GlobalConstant) {
-  ParserImpl p{"const a : i32 = 2;"};
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("const a : i32 = 2;");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(m.global_variables().size(), 1);
 
   auto v = m.global_variables()[0].get();
@@ -95,82 +94,82 @@
 }
 
 TEST_F(ParserImplTest, GlobalDecl_GlobalConstant_Invalid) {
-  ParserImpl p{"const a : vec2<i32>;"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:20: missing = for const declaration");
+  auto p = parser("const a : vec2<i32>;");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:20: missing = for const declaration");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_GlobalConstant_MissingSemicolon) {
-  ParserImpl p{"const a : vec2<i32> = vec2<i32>(1, 2)"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:38: missing ';' for constant declaration");
+  auto p = parser("const a : vec2<i32> = vec2<i32>(1, 2)");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:38: missing ';' for constant declaration");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_EntryPoint) {
-  ParserImpl p{"entry_point vertex = main;"};
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("entry_point vertex = main;");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(m.entry_points().size(), 1);
   EXPECT_EQ(m.entry_points()[0]->name(), "main");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_EntryPoint_Invalid) {
-  ParserImpl p{"entry_point main;"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:13: missing pipeline stage for entry point");
+  auto p = parser("entry_point main;");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:13: missing pipeline stage for entry point");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_EntryPoint_MissingSemicolon) {
-  ParserImpl p{"entry_point vertex = main"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:26: missing ';' for entry point");
+  auto p = parser("entry_point vertex = main");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:26: missing ';' for entry point");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_TypeAlias) {
-  ParserImpl p{"type A = i32;"};
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("type A = i32;");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(m.alias_types().size(), 1);
   EXPECT_EQ(m.alias_types()[0]->name(), "A");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_TypeAlias_Invalid) {
-  ParserImpl p{"type A = invalid;"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:10: unknown type alias 'invalid'");
+  auto p = parser("type A = invalid;");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:10: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_TypeAlias_MissingSemicolon) {
-  ParserImpl p{"type A = i32"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:13: missing ';' for type alias");
+  auto p = parser("type A = i32");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:13: missing ';' for type alias");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_Function) {
-  ParserImpl p{"fn main() -> void { return; }"};
-  p.global_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("fn main() -> void { return; }");
+  p->global_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(m.functions().size(), 1);
   EXPECT_EQ(m.functions()[0]->name(), "main");
 }
 
 TEST_F(ParserImplTest, GlobalDecl_Function_Invalid) {
-  ParserImpl p{"fn main() -> { return; }"};
-  p.global_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:14: unable to determine function return type");
+  auto p = parser("fn main() -> { return; }");
+  p->global_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:14: unable to determine function return type");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_global_variable_decl_test.cc b/src/reader/wgsl/parser_impl_global_variable_decl_test.cc
index 528135c..3bd2d95 100644
--- a/src/reader/wgsl/parser_impl_global_variable_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_global_variable_decl_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/decorated_variable.h"
 #include "src/ast/variable_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, GlobalVariableDecl_WithoutInitializer) {
-  ParserImpl p{"var<out> a : f32"};
-  auto e = p.global_variable_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("var<out> a : f32");
+  auto e = p->global_variable_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   EXPECT_EQ(e->name(), "a");
@@ -38,9 +37,9 @@
 }
 
 TEST_F(ParserImplTest, GlobalVariableDecl_WithInitializer) {
-  ParserImpl p{"var<out> a : f32 = 1."};
-  auto e = p.global_variable_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("var<out> a : f32 = 1.");
+  auto e = p->global_variable_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   EXPECT_EQ(e->name(), "a");
@@ -55,9 +54,9 @@
 }
 
 TEST_F(ParserImplTest, GlobalVariableDecl_WithDecoration) {
-  ParserImpl p{"[[binding 2, set 1]] var<out> a : f32"};
-  auto e = p.global_variable_decl();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("[[binding 2, set 1]] var<out> a : f32");
+  auto e = p->global_variable_decl();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsDecorated());
 
@@ -78,27 +77,27 @@
 }
 
 TEST_F(ParserImplTest, GlobalVariableDecl_InvalidDecoration) {
-  ParserImpl p{"[[binding]] var<out> a : f32"};
-  auto e = p.global_variable_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("[[binding]] var<out> a : f32");
+  auto e = p->global_variable_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: invalid value for binding decoration");
+  EXPECT_EQ(p->error(), "1:10: invalid value for binding decoration");
 }
 
 TEST_F(ParserImplTest, GlobalVariableDecl_InvalidConstExpr) {
-  ParserImpl p{"var<out> a : f32 = if (a) {}"};
-  auto e = p.global_variable_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var<out> a : f32 = if (a) {}");
+  auto e = p->global_variable_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:20: unable to parse const literal");
+  EXPECT_EQ(p->error(), "1:20: unable to parse const literal");
 }
 
 TEST_F(ParserImplTest, GlobalVariableDecl_InvalidVariableDecl) {
-  ParserImpl p{"var<invalid> a : f32;"};
-  auto e = p.global_variable_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var<invalid> a : f32;");
+  auto e = p->global_variable_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: invalid storage class for variable decoration");
+  EXPECT_EQ(p->error(), "1:5: invalid storage class for variable decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_if_stmt_test.cc b/src/reader/wgsl/parser_impl_if_stmt_test.cc
index 32fa433..fcca219 100644
--- a/src/reader/wgsl/parser_impl_if_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_if_stmt_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/else_statement.h"
 #include "src/ast/if_statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, IfStmt) {
-  ParserImpl p{"if (a == 4) { a = b; c = d; }"};
-  auto e = p.if_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a == 4) { a = b; c = d; }");
+  auto e = p->if_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsIf());
@@ -38,9 +37,9 @@
 }
 
 TEST_F(ParserImplTest, IfStmt_WithElse) {
-  ParserImpl p{"if (a == 4) { a = b; c = d; } elseif(c) { d = 2; } else {}"};
-  auto e = p.if_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a == 4) { a = b; c = d; } elseif(c) { d = 2; } else {}");
+  auto e = p->if_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsIf());
@@ -58,16 +57,16 @@
 }
 
 TEST_F(ParserImplTest, IfStmt_WithPremerge) {
-  ParserImpl p{R"(if (a == 4) {
+  auto p = parser(R"(if (a == 4) {
   a = b;
   c = d;
 } else {
   d = 2;
 } premerge {
   a = 2;
-})"};
-  auto e = p.if_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+})");
+  auto e = p->if_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsIf());
@@ -83,59 +82,59 @@
 }
 
 TEST_F(ParserImplTest, IfStmt_InvalidCondition) {
-  ParserImpl p{"if (a = 3) {}"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a = 3) {}");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:7: expected )");
+  EXPECT_EQ(p->error(), "1:7: expected )");
 }
 
 TEST_F(ParserImplTest, IfStmt_MissingCondition) {
-  ParserImpl p{"if {}"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if {}");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:4: expected (");
+  EXPECT_EQ(p->error(), "1:4: expected (");
 }
 
 TEST_F(ParserImplTest, IfStmt_InvalidBody) {
-  ParserImpl p{"if (a) { fn main() -> void {}}"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a) { fn main() -> void {}}");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: missing }");
+  EXPECT_EQ(p->error(), "1:10: missing }");
 }
 
 TEST_F(ParserImplTest, IfStmt_MissingBody) {
-  ParserImpl p{"if (a)"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a)");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:7: missing {");
+  EXPECT_EQ(p->error(), "1:7: missing {");
 }
 
 TEST_F(ParserImplTest, IfStmt_InvalidElseif) {
-  ParserImpl p{"if (a) {} elseif (a) { fn main() -> a{}}"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a) {} elseif (a) { fn main() -> a{}}");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:24: missing }");
+  EXPECT_EQ(p->error(), "1:24: missing }");
 }
 
 TEST_F(ParserImplTest, IfStmt_InvalidElse) {
-  ParserImpl p{"if (a) {} else { fn main() -> a{}}"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a) {} else { fn main() -> a{}}");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:18: missing }");
+  EXPECT_EQ(p->error(), "1:18: missing }");
 }
 
 TEST_F(ParserImplTest, IfStmt_InvalidPremerge) {
-  ParserImpl p{"if (a) {} else {} premerge { fn main() -> a{}}"};
-  auto e = p.if_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a) {} else {} premerge { fn main() -> a{}}");
+  auto e = p->if_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:30: missing }");
+  EXPECT_EQ(p->error(), "1:30: missing }");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_import_decl_test.cc b/src/reader/wgsl/parser_impl_import_decl_test.cc
index bfd6cc9..9f124fb 100644
--- a/src/reader/wgsl/parser_impl_import_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_import_decl_test.cc
@@ -14,19 +14,18 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ImportDecl_Import) {
-  ParserImpl p{R"(import "GLSL.std.450" as glsl)"};
+  auto p = parser(R"(import "GLSL.std.450" as glsl)");
 
-  auto import = p.import_decl();
+  auto import = p->import_decl();
   ASSERT_NE(import, nullptr);
-  ASSERT_FALSE(p.has_error()) << p.error();
+  ASSERT_FALSE(p->has_error()) << p->error();
 
   EXPECT_EQ("GLSL.std.450", import->path());
   EXPECT_EQ("glsl", import->name());
@@ -35,59 +34,59 @@
 }
 
 TEST_F(ParserImplTest, ImportDecl_Import_WithNamespace) {
-  ParserImpl p{R"(import "GLSL.std.450" as std::glsl)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import "GLSL.std.450" as std::glsl)");
+  auto import = p->import_decl();
   ASSERT_NE(import, nullptr);
-  ASSERT_FALSE(p.has_error()) << p.error();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_EQ("std::glsl", import->name());
 }
 
 TEST_F(ParserImplTest, ImportDecl_Invalid_MissingPath) {
-  ParserImpl p{R"(import as glsl)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import as glsl)");
+  auto import = p->import_decl();
   ASSERT_EQ(import, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: missing path for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: missing path for import");
 }
 
 TEST_F(ParserImplTest, ImportDecl_Invalid_EmptyPath) {
-  ParserImpl p{R"(import "" as glsl)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import "" as glsl)");
+  auto import = p->import_decl();
   ASSERT_EQ(import, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: import path must not be empty");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: import path must not be empty");
 }
 
 TEST_F(ParserImplTest, ImportDecl_Invalid_NameMissingTerminatingIdentifier) {
-  ParserImpl p{R"(import "GLSL.std.450" as glsl::)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import "GLSL.std.450" as glsl::)");
+  auto import = p->import_decl();
   ASSERT_EQ(import, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:32: invalid name for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:32: invalid name for import");
 }
 
 TEST_F(ParserImplTest, ImportDecl_Invalid_NameInvalid) {
-  ParserImpl p{R"(import "GLSL.std.450" as 12glsl)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import "GLSL.std.450" as 12glsl)");
+  auto import = p->import_decl();
   ASSERT_EQ(import, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:26: invalid name for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:26: invalid name for import");
 }
 
 TEST_F(ParserImplTest, ImportDecl_Invalid_MissingName) {
-  ParserImpl p{R"(import "GLSL.std.450" as)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import "GLSL.std.450" as)");
+  auto import = p->import_decl();
   ASSERT_EQ(import, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:25: missing name for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:25: missing name for import");
 }
 
 TEST_F(ParserImplTest, ImportDecl_Invalid_MissingAs) {
-  ParserImpl p{R"(import "GLSL.std.450" glsl)"};
-  auto import = p.import_decl();
+  auto p = parser(R"(import "GLSL.std.450" glsl)");
+  auto import = p->import_decl();
   ASSERT_EQ(import, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:23: missing 'as' for import");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:23: missing 'as' for import");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_inclusive_or_expression_test.cc b/src/reader/wgsl/parser_impl_inclusive_or_expression_test.cc
index 38223fb..bc03c80 100644
--- a/src/reader/wgsl/parser_impl_inclusive_or_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_inclusive_or_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, InclusiveOrExpression_Parses) {
-  ParserImpl p{"a | true"};
-  auto e = p.inclusive_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a | true");
+  auto e = p->inclusive_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,24 +47,24 @@
 }
 
 TEST_F(ParserImplTest, InclusiveOrExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} | true"};
-  auto e = p.inclusive_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} | true");
+  auto e = p->inclusive_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, InclusiveOrExpression_InvalidRHS) {
-  ParserImpl p{"true | if (a) {}"};
-  auto e = p.inclusive_or_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true | if (a) {}");
+  auto e = p->inclusive_or_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse right side of | expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse right side of | expression");
 }
 
 TEST_F(ParserImplTest, InclusiveOrExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.inclusive_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->inclusive_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_logical_and_expression_test.cc b/src/reader/wgsl/parser_impl_logical_and_expression_test.cc
index c48cca5..3961a5e 100644
--- a/src/reader/wgsl/parser_impl_logical_and_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_logical_and_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, LogicalAndExpression_Parses) {
-  ParserImpl p{"a && true"};
-  auto e = p.logical_and_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a && true");
+  auto e = p->logical_and_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,24 +47,24 @@
 }
 
 TEST_F(ParserImplTest, LogicalAndExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} && true"};
-  auto e = p.logical_and_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} && true");
+  auto e = p->logical_and_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, LogicalAndExpression_InvalidRHS) {
-  ParserImpl p{"true && if (a) {}"};
-  auto e = p.logical_and_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true && if (a) {}");
+  auto e = p->logical_and_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse right side of && expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse right side of && expression");
 }
 
 TEST_F(ParserImplTest, LogicalAndExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.logical_and_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->logical_and_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_logical_or_expression_test.cc b/src/reader/wgsl/parser_impl_logical_or_expression_test.cc
index 9c90b66..3de18d4 100644
--- a/src/reader/wgsl/parser_impl_logical_or_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_logical_or_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, LogicalOrExpression_Parses) {
-  ParserImpl p{"a || true"};
-  auto e = p.logical_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a || true");
+  auto e = p->logical_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,24 +47,24 @@
 }
 
 TEST_F(ParserImplTest, LogicalOrExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} || true"};
-  auto e = p.logical_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} || true");
+  auto e = p->logical_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, LogicalOrExpression_InvalidRHS) {
-  ParserImpl p{"true || if (a) {}"};
-  auto e = p.logical_or_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true || if (a) {}");
+  auto e = p->logical_or_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse right side of || expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse right side of || expression");
 }
 
 TEST_F(ParserImplTest, LogicalOrExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.logical_or_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->logical_or_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_loop_stmt_test.cc b/src/reader/wgsl/parser_impl_loop_stmt_test.cc
index 8896582..7520c4f 100644
--- a/src/reader/wgsl/parser_impl_loop_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_loop_stmt_test.cc
@@ -14,17 +14,16 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, LoopStmt_BodyNoContinuing) {
-  ParserImpl p{"loop { nop; }"};
-  auto e = p.loop_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("loop { nop; }");
+  auto e = p->loop_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_EQ(e->body().size(), 1);
@@ -34,9 +33,9 @@
 }
 
 TEST_F(ParserImplTest, LoopStmt_BodyWithContinuing) {
-  ParserImpl p{"loop { nop; continuing { kill; }}"};
-  auto e = p.loop_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("loop { nop; continuing { kill; }}");
+  auto e = p->loop_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_EQ(e->body().size(), 1);
@@ -47,18 +46,18 @@
 }
 
 TEST_F(ParserImplTest, LoopStmt_NoBodyNoContinuing) {
-  ParserImpl p{"loop { }"};
-  auto e = p.loop_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("loop { }");
+  auto e = p->loop_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_EQ(e->body().size(), 0);
   ASSERT_EQ(e->continuing().size(), 0);
 }
 
 TEST_F(ParserImplTest, LoopStmt_NoBodyWithContinuing) {
-  ParserImpl p{"loop { continuing { kill; }}"};
-  auto e = p.loop_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("loop { continuing { kill; }}");
+  auto e = p->loop_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_EQ(e->body().size(), 0);
   ASSERT_EQ(e->continuing().size(), 1);
@@ -66,35 +65,35 @@
 }
 
 TEST_F(ParserImplTest, LoopStmt_MissingBracketLeft) {
-  ParserImpl p{"loop kill; }"};
-  auto e = p.loop_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("loop kill; }");
+  auto e = p->loop_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing { for loop");
+  EXPECT_EQ(p->error(), "1:6: missing { for loop");
 }
 
 TEST_F(ParserImplTest, LoopStmt_MissingBracketRight) {
-  ParserImpl p{"loop { kill; "};
-  auto e = p.loop_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("loop { kill; ");
+  auto e = p->loop_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing } for loop");
+  EXPECT_EQ(p->error(), "1:14: missing } for loop");
 }
 
 TEST_F(ParserImplTest, LoopStmt_InvalidStatements) {
-  ParserImpl p{"loop { kill }"};
-  auto e = p.loop_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("loop { kill }");
+  auto e = p->loop_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing ;");
+  EXPECT_EQ(p->error(), "1:13: missing ;");
 }
 
 TEST_F(ParserImplTest, LoopStmt_InvalidContinuing) {
-  ParserImpl p{"loop { continuing { kill }}"};
-  auto e = p.loop_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("loop { continuing { kill }}");
+  auto e = p->loop_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:26: missing ;");
+  EXPECT_EQ(p->error(), "1:26: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_multiplicative_expression_test.cc b/src/reader/wgsl/parser_impl_multiplicative_expression_test.cc
index bf32a1d..530806d 100644
--- a/src/reader/wgsl/parser_impl_multiplicative_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_multiplicative_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, MultiplicativeExpression_Parses_Multiply) {
-  ParserImpl p{"a * true"};
-  auto e = p.multiplicative_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a * true");
+  auto e = p->multiplicative_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,9 +47,9 @@
 }
 
 TEST_F(ParserImplTest, MultiplicativeExpression_Parses_Divide) {
-  ParserImpl p{"a / true"};
-  auto e = p.multiplicative_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a / true");
+  auto e = p->multiplicative_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -70,9 +69,9 @@
 }
 
 TEST_F(ParserImplTest, MultiplicativeExpression_Parses_Modulo) {
-  ParserImpl p{"a % true"};
-  auto e = p.multiplicative_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a % true");
+  auto e = p->multiplicative_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -92,24 +91,24 @@
 }
 
 TEST_F(ParserImplTest, MultiplicativeExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} * true"};
-  auto e = p.multiplicative_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} * true");
+  auto e = p->multiplicative_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, MultiplicativeExpression_InvalidRHS) {
-  ParserImpl p{"true * if (a) {}"};
-  auto e = p.multiplicative_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true * if (a) {}");
+  auto e = p->multiplicative_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse right side of * expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse right side of * expression");
 }
 
 TEST_F(ParserImplTest, MultiplicativeExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.multiplicative_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->multiplicative_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_param_list_test.cc b/src/reader/wgsl/parser_impl_param_list_test.cc
index 05f4acd..0c7702b 100644
--- a/src/reader/wgsl/parser_impl_param_list_test.cc
+++ b/src/reader/wgsl/parser_impl_param_list_test.cc
@@ -20,38 +20,33 @@
 #include "src/ast/type/vector_type.h"
 #include "src/ast/variable.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ParamList_Single) {
-  auto tm = TypeManager::Instance();
-  auto i32 = tm->Get(std::make_unique<ast::type::I32Type>());
+  auto i32 = tm()->Get(std::make_unique<ast::type::I32Type>());
 
-  ParserImpl p{"a : i32"};
-  auto e = p.param_list();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a : i32");
+  auto e = p->param_list();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_EQ(e.size(), 1);
 
   EXPECT_EQ(e[0]->name(), "a");
   EXPECT_EQ(e[0]->type(), i32);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, ParamList_Multiple) {
-  auto tm = TypeManager::Instance();
-  auto i32 = tm->Get(std::make_unique<ast::type::I32Type>());
-  auto f32 = tm->Get(std::make_unique<ast::type::F32Type>());
-  auto vec2 = tm->Get(std::make_unique<ast::type::VectorType>(f32, 2));
+  auto i32 = tm()->Get(std::make_unique<ast::type::I32Type>());
+  auto f32 = tm()->Get(std::make_unique<ast::type::F32Type>());
+  auto vec2 = tm()->Get(std::make_unique<ast::type::VectorType>(f32, 2));
 
-  ParserImpl p{"a : i32, b: f32, c: vec2<f32>"};
-  auto e = p.param_list();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a : i32, b: f32, c: vec2<f32>");
+  auto e = p->param_list();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_EQ(e.size(), 3);
 
   EXPECT_EQ(e[0]->name(), "a");
@@ -62,22 +57,20 @@
 
   EXPECT_EQ(e[2]->name(), "c");
   EXPECT_EQ(e[2]->type(), vec2);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, ParamList_Empty) {
-  ParserImpl p{""};
-  auto e = p.param_list();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("");
+  auto e = p->param_list();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_EQ(e.size(), 0);
 }
 
 TEST_F(ParserImplTest, ParamList_HangingComma) {
-  ParserImpl p{"a : i32,"};
-  auto e = p.param_list();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: found , but no variable declaration");
+  auto p = parser("a : i32,");
+  auto e = p->param_list();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: found , but no variable declaration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_paren_rhs_stmt_test.cc b/src/reader/wgsl/parser_impl_paren_rhs_stmt_test.cc
index 42cae73..e19fe96 100644
--- a/src/reader/wgsl/parser_impl_paren_rhs_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_paren_rhs_stmt_test.cc
@@ -14,51 +14,50 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ParenRhsStmt) {
-  ParserImpl p{"(a + b)"};
-  auto e = p.paren_rhs_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("(a + b)");
+  auto e = p->paren_rhs_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsRelational());
 }
 
 TEST_F(ParserImplTest, ParenRhsStmt_MissingLeftParen) {
-  ParserImpl p{"true)"};
-  auto e = p.paren_rhs_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true)");
+  auto e = p->paren_rhs_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:1: expected (");
+  EXPECT_EQ(p->error(), "1:1: expected (");
 }
 
 TEST_F(ParserImplTest, ParenRhsStmt_MissingRightParen) {
-  ParserImpl p{"(true"};
-  auto e = p.paren_rhs_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("(true");
+  auto e = p->paren_rhs_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: expected )");
+  EXPECT_EQ(p->error(), "1:6: expected )");
 }
 
 TEST_F(ParserImplTest, ParenRhsStmt_InvalidExpression) {
-  ParserImpl p{"(if (a() {})"};
-  auto e = p.paren_rhs_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("(if (a() {})");
+  auto e = p->paren_rhs_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:2: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:2: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, ParenRhsStmt_MissingExpression) {
-  ParserImpl p{"()"};
-  auto e = p.paren_rhs_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("()");
+  auto e = p->paren_rhs_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:2: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:2: unable to parse expression");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_pipeline_stage_test.cc b/src/reader/wgsl/parser_impl_pipeline_stage_test.cc
index fc4983c..53ede15 100644
--- a/src/reader/wgsl/parser_impl_pipeline_stage_test.cc
+++ b/src/reader/wgsl/parser_impl_pipeline_stage_test.cc
@@ -15,12 +15,12 @@
 #include "gtest/gtest.h"
 #include "src/ast/pipeline_stage.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
-
-using ParserImplTest = testing::Test;
+namespace {
 
 struct PipelineStageData {
   const char* input;
@@ -30,16 +30,41 @@
   out << std::string(data.input);
   return out;
 }
-using PipelineStageTest = testing::TestWithParam<PipelineStageData>;
+
+class PipelineStageTest : public testing::TestWithParam<PipelineStageData> {
+ public:
+  PipelineStageTest() = default;
+  ~PipelineStageTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace
+
 TEST_P(PipelineStageTest, Parses) {
   auto params = GetParam();
-  ParserImpl p{params.input};
+  auto p = parser(params.input);
 
-  auto stage = p.pipeline_stage();
-  ASSERT_FALSE(p.has_error());
+  auto stage = p->pipeline_stage();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(stage, params.result);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsEof());
 }
 INSTANTIATE_TEST_SUITE_P(
@@ -51,11 +76,11 @@
         PipelineStageData{"compute", ast::PipelineStage::kCompute}));
 
 TEST_F(ParserImplTest, PipelineStage_NoMatch) {
-  ParserImpl p{"not-a-stage"};
-  auto stage = p.pipeline_stage();
+  auto p = parser("not-a-stage");
+  auto stage = p->pipeline_stage();
   ASSERT_EQ(stage, ast::PipelineStage::kNone);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsIdentifier());
   EXPECT_EQ(t.to_str(), "not");
 }
diff --git a/src/reader/wgsl/parser_impl_postfix_expression_test.cc b/src/reader/wgsl/parser_impl_postfix_expression_test.cc
index 01782ee..47611b0 100644
--- a/src/reader/wgsl/parser_impl_postfix_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_postfix_expression_test.cc
@@ -23,17 +23,16 @@
 #include "src/ast/unary_method_expression.h"
 #include "src/ast/unary_op_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, PostfixExpression_Array_ConstantIndex) {
-  ParserImpl p{"a[1]"};
-  auto e = p.postfix_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a[1]");
+  auto e = p->postfix_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsArrayAccessor());
@@ -52,9 +51,9 @@
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Array_ExpressionIndex) {
-  ParserImpl p{"a[1 + b / 4]"};
-  auto e = p.postfix_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a[1 + b / 4]");
+  auto e = p->postfix_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsArrayAccessor());
@@ -69,33 +68,33 @@
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Array_MissingIndex) {
-  ParserImpl p{"a[]"};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a[]");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:3: unable to parse expression inside []");
+  EXPECT_EQ(p->error(), "1:3: unable to parse expression inside []");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Array_MissingRightBrace) {
-  ParserImpl p{"a[1"};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a[1");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:4: missing ] for array accessor");
+  EXPECT_EQ(p->error(), "1:4: missing ] for array accessor");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Array_InvalidIndex) {
-  ParserImpl p{"a[if(a() {})]"};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a[if(a() {})]");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:3: unable to parse expression inside []");
+  EXPECT_EQ(p->error(), "1:3: unable to parse expression inside []");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Call_Empty) {
-  ParserImpl p{"a()"};
-  auto e = p.postfix_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a()");
+  auto e = p->postfix_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsCall());
@@ -110,9 +109,9 @@
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Call_WithArgs) {
-  ParserImpl p{"std::test(1, b, 2 + 3 / b)"};
-  auto e = p.postfix_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("std::test(1, b, 2 + 3 / b)");
+  auto e = p->postfix_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsCall());
@@ -131,33 +130,33 @@
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Call_InvalidArg) {
-  ParserImpl p{"a(if(a) {})"};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a(if(a) {})");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:3: unable to parse argument expression");
+  EXPECT_EQ(p->error(), "1:3: unable to parse argument expression");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Call_HangingComma) {
-  ParserImpl p{"a(b, )"};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a(b, )");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unable to parse argument expression after comma");
+  EXPECT_EQ(p->error(), "1:6: unable to parse argument expression after comma");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_Call_MissingRightParen) {
-  ParserImpl p{"a("};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a(");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:3: missing ) for call expression");
+  EXPECT_EQ(p->error(), "1:3: missing ) for call expression");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_MemberAccessor) {
-  ParserImpl p{"a.b"};
-  auto e = p.postfix_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a.b");
+  auto e = p->postfix_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsMemberAccessor());
 
@@ -172,25 +171,25 @@
 }
 
 TEST_F(ParserImplTest, PostfixExpression_MemberAccesssor_InvalidIdent) {
-  ParserImpl p{"a.if"};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a.if");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:3: missing identifier for member accessor");
+  EXPECT_EQ(p->error(), "1:3: missing identifier for member accessor");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_MemberAccessor_MissingIdent) {
-  ParserImpl p{"a."};
-  auto e = p.postfix_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a.");
+  auto e = p->postfix_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:3: missing identifier for member accessor");
+  EXPECT_EQ(p->error(), "1:3: missing identifier for member accessor");
 }
 
 TEST_F(ParserImplTest, PostfixExpression_NonMatch_returnLHS) {
-  ParserImpl p{"a b"};
-  auto e = p.postfix_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a b");
+  auto e = p->postfix_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_premerge_stmt_test.cc b/src/reader/wgsl/parser_impl_premerge_stmt_test.cc
index 55c3744..9688c06 100644
--- a/src/reader/wgsl/parser_impl_premerge_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_premerge_stmt_test.cc
@@ -14,27 +14,26 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, PremergeStmt) {
-  ParserImpl p{"premerge { nop; }"};
-  auto e = p.premerge_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("premerge { nop; }");
+  auto e = p->premerge_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 1);
   ASSERT_TRUE(e[0]->IsNop());
 }
 
 TEST_F(ParserImplTest, PremergeStmt_InvalidBody) {
-  ParserImpl p{"premerge { nop }"};
-  auto e = p.premerge_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("premerge { nop }");
+  auto e = p->premerge_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e.size(), 0);
-  EXPECT_EQ(p.error(), "1:16: missing ;");
+  EXPECT_EQ(p->error(), "1:16: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_primary_expression_test.cc b/src/reader/wgsl/parser_impl_primary_expression_test.cc
index f9d676a..824fd2b 100644
--- a/src/reader/wgsl/parser_impl_primary_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_primary_expression_test.cc
@@ -27,18 +27,17 @@
 #include "src/ast/unary_method_expression.h"
 #include "src/ast/unary_op_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, PrimaryExpression_Ident) {
-  ParserImpl p{"a"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
   auto ident = e->AsIdentifier();
@@ -47,9 +46,9 @@
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Ident_WithNamespace) {
-  ParserImpl p{"a::b::c::d"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a::b::c::d");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
   auto ident = e->AsIdentifier();
@@ -61,17 +60,17 @@
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Ident_MissingIdent) {
-  ParserImpl p{"a::"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a::");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:4: identifier expected");
+  EXPECT_EQ(p->error(), "1:4: identifier expected");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_TypeDecl) {
-  ParserImpl p{"vec4<i32>(1, 2, 3, 4))"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("vec4<i32>(1, 2, 3, 4))");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsInitializer());
   ASSERT_TRUE(e->AsInitializer()->IsTypeInitializer());
@@ -105,41 +104,41 @@
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_TypeDecl_InvalidTypeDecl) {
-  ParserImpl p{"vec4<if>(2., 3., 4., 5.)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec4<if>(2., 3., 4., 5.)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unable to determine subtype for vector");
+  EXPECT_EQ(p->error(), "1:6: unable to determine subtype for vector");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_TypeDecl_MissingLeftParen) {
-  ParserImpl p{"vec4<f32> 2., 3., 4., 5.)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec4<f32> 2., 3., 4., 5.)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing ( for type initializer");
+  EXPECT_EQ(p->error(), "1:11: missing ( for type initializer");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_TypeDecl_MissingRightParen) {
-  ParserImpl p{"vec4<f32>(2., 3., 4., 5."};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("vec4<f32>(2., 3., 4., 5.");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:25: missing ) for type initializer");
+  EXPECT_EQ(p->error(), "1:25: missing ) for type initializer");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_TypeDecl_InvalidValue) {
-  ParserImpl p{"i32(if(a) {})"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("i32(if(a) {})");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: unable to parse argument expression");
+  EXPECT_EQ(p->error(), "1:5: unable to parse argument expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_ConstLiteral_True) {
-  ParserImpl p{"true"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("true");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsInitializer());
   ASSERT_TRUE(e->AsInitializer()->IsConstInitializer());
@@ -149,44 +148,43 @@
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_ParenExpr) {
-  ParserImpl p{"(a == b)"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("(a == b)");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsRelational());
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_ParenExpr_MissingRightParen) {
-  ParserImpl p{"(a == b"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("(a == b");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: expected )");
+  EXPECT_EQ(p->error(), "1:8: expected )");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_ParenExpr_MissingExpr) {
-  ParserImpl p{"()"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("()");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:2: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:2: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_ParenExpr_InvalidExpr) {
-  ParserImpl p{"(if (a) {})"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("(if (a) {})");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:2: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:2: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast) {
-  auto tm = TypeManager::Instance();
-  auto f32_type = tm->Get(std::make_unique<ast::type::F32Type>());
+  auto f32_type = tm()->Get(std::make_unique<ast::type::F32Type>());
 
-  ParserImpl p{"cast<f32>(1)"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("cast<f32>(1)");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsCast());
 
@@ -195,73 +193,70 @@
 
   ASSERT_TRUE(c->expr()->IsInitializer());
   ASSERT_TRUE(c->expr()->AsInitializer()->IsConstInitializer());
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_MissingGreaterThan) {
-  ParserImpl p{"cast<f32(1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<f32(1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing > for cast expression");
+  EXPECT_EQ(p->error(), "1:9: missing > for cast expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_MissingType) {
-  ParserImpl p{"cast<>(1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<>(1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing type for cast expression");
+  EXPECT_EQ(p->error(), "1:6: missing type for cast expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_InvalidType) {
-  ParserImpl p{"cast<invalid>(1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<invalid>(1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:6: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_MissingLeftParen) {
-  ParserImpl p{"cast<f32>1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<f32>1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: expected (");
+  EXPECT_EQ(p->error(), "1:10: expected (");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_MissingRightParen) {
-  ParserImpl p{"cast<f32>(1"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<f32>(1");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: expected )");
+  EXPECT_EQ(p->error(), "1:12: expected )");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_MissingExpression) {
-  ParserImpl p{"cast<f32>()"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<f32>()");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:11: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_Cast_InvalidExpression) {
-  ParserImpl p{"cast<f32>(if (a) {})"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("cast<f32>(if (a) {})");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:11: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As) {
-  auto tm = TypeManager::Instance();
-  auto f32_type = tm->Get(std::make_unique<ast::type::F32Type>());
+  auto f32_type = tm()->Get(std::make_unique<ast::type::F32Type>());
 
-  ParserImpl p{"as<f32>(1)"};
-  auto e = p.primary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("as<f32>(1)");
+  auto e = p->primary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsAs());
 
@@ -270,64 +265,62 @@
 
   ASSERT_TRUE(c->expr()->IsInitializer());
   ASSERT_TRUE(c->expr()->AsInitializer()->IsConstInitializer());
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_MissingGreaterThan) {
-  ParserImpl p{"as<f32(1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<f32(1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:7: missing > for as expression");
+  EXPECT_EQ(p->error(), "1:7: missing > for as expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_MissingType) {
-  ParserImpl p{"as<>(1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<>(1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:4: missing type for as expression");
+  EXPECT_EQ(p->error(), "1:4: missing type for as expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_InvalidType) {
-  ParserImpl p{"as<invalid>(1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<invalid>(1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:4: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:4: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_MissingLeftParen) {
-  ParserImpl p{"as<f32>1)"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<f32>1)");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: expected (");
+  EXPECT_EQ(p->error(), "1:8: expected (");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_MissingRightParen) {
-  ParserImpl p{"as<f32>(1"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<f32>(1");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: expected )");
+  EXPECT_EQ(p->error(), "1:10: expected )");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_MissingExpression) {
-  ParserImpl p{"as<f32>()"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<f32>()");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, PrimaryExpression_As_InvalidExpression) {
-  ParserImpl p{"as<f32>(if (a) {})"};
-  auto e = p.primary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("as<f32>(if (a) {})");
+  auto e = p->primary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse expression");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_regardless_stmt_test.cc b/src/reader/wgsl/parser_impl_regardless_stmt_test.cc
index ea2f05b..92aa8c8 100644
--- a/src/reader/wgsl/parser_impl_regardless_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_regardless_stmt_test.cc
@@ -14,17 +14,16 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, RegardlessStmt) {
-  ParserImpl p{"regardless (a) { kill; }"};
-  auto e = p.regardless_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("regardless (a) { kill; }");
+  auto e = p->regardless_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsRegardless());
   ASSERT_NE(e->condition(), nullptr);
@@ -34,27 +33,27 @@
 }
 
 TEST_F(ParserImplTest, RegardlessStmt_InvalidCondition) {
-  ParserImpl p{"regardless(if(a){}) {}"};
-  auto e = p.regardless_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("regardless(if(a){}) {}");
+  auto e = p->regardless_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:12: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, RegardlessStmt_EmptyCondition) {
-  ParserImpl p{"regardless() {}"};
-  auto e = p.regardless_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("regardless() {}");
+  auto e = p->regardless_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:12: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, RegardlessStmt_InvalidBody) {
-  ParserImpl p{"regardless(a + 2 - 5 == true) { kill }"};
-  auto e = p.regardless_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("regardless(a + 2 - 5 == true) { kill }");
+  auto e = p->regardless_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:38: missing ;");
+  EXPECT_EQ(p->error(), "1:38: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_relational_expression_test.cc b/src/reader/wgsl/parser_impl_relational_expression_test.cc
index 8f236b0..3b3a148 100644
--- a/src/reader/wgsl/parser_impl_relational_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_relational_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, RelationalExpression_Parses_LessThan) {
-  ParserImpl p{"a < true"};
-  auto e = p.relational_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a < true");
+  auto e = p->relational_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,9 +47,9 @@
 }
 
 TEST_F(ParserImplTest, RelationalExpression_Parses_GreaterThan) {
-  ParserImpl p{"a > true"};
-  auto e = p.relational_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a > true");
+  auto e = p->relational_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -70,9 +69,9 @@
 }
 
 TEST_F(ParserImplTest, RelationalExpression_Parses_LessThanEqual) {
-  ParserImpl p{"a <= true"};
-  auto e = p.relational_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a <= true");
+  auto e = p->relational_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -92,9 +91,9 @@
 }
 
 TEST_F(ParserImplTest, RelationalExpression_Parses_GreaterThanEqual) {
-  ParserImpl p{"a >= true"};
-  auto e = p.relational_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a >= true");
+  auto e = p->relational_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -114,24 +113,24 @@
 }
 
 TEST_F(ParserImplTest, RelationalExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} < true"};
-  auto e = p.relational_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} < true");
+  auto e = p->relational_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, RelationalExpression_InvalidRHS) {
-  ParserImpl p{"true < if (a) {}"};
-  auto e = p.relational_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true < if (a) {}");
+  auto e = p->relational_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse right side of < expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse right side of < expression");
 }
 
 TEST_F(ParserImplTest, RelationalExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.relational_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->relational_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_shift_expression_test.cc b/src/reader/wgsl/parser_impl_shift_expression_test.cc
index 21fe620..e9d7273 100644
--- a/src/reader/wgsl/parser_impl_shift_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_shift_expression_test.cc
@@ -18,17 +18,16 @@
 #include "src/ast/identifier_expression.h"
 #include "src/ast/relational_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftLeft) {
-  ParserImpl p{"a << true"};
-  auto e = p.shift_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a << true");
+  auto e = p->shift_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -48,9 +47,9 @@
 }
 
 TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftRight) {
-  ParserImpl p{"a >> true"};
-  auto e = p.shift_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a >> true");
+  auto e = p->shift_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -70,9 +69,9 @@
 }
 
 TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftRightArith) {
-  ParserImpl p{"a >>> true"};
-  auto e = p.shift_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a >>> true");
+  auto e = p->shift_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsRelational());
@@ -92,24 +91,24 @@
 }
 
 TEST_F(ParserImplTest, ShiftExpression_InvalidLHS) {
-  ParserImpl p{"if (a) {} << true"};
-  auto e = p.shift_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {} << true");
+  auto e = p->shift_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, ShiftExpression_InvalidRHS) {
-  ParserImpl p{"true << if (a) {}"};
-  auto e = p.shift_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("true << if (a) {}");
+  auto e = p->shift_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse right side of << expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse right side of << expression");
 }
 
 TEST_F(ParserImplTest, ShiftExpression_NoOr_ReturnsLHS) {
-  ParserImpl p{"a true"};
-  auto e = p.shift_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a true");
+  auto e = p->shift_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIdentifier());
 }
diff --git a/src/reader/wgsl/parser_impl_statement_test.cc b/src/reader/wgsl/parser_impl_statement_test.cc
index 005eb82..e5f8457 100644
--- a/src/reader/wgsl/parser_impl_statement_test.cc
+++ b/src/reader/wgsl/parser_impl_statement_test.cc
@@ -16,32 +16,31 @@
 #include "src/ast/return_statement.h"
 #include "src/ast/statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, Statement) {
-  ParserImpl p{"return;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("return;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   EXPECT_TRUE(e->IsReturn());
 }
 
 TEST_F(ParserImplTest, Statement_Semicolon) {
-  ParserImpl p{";"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser(";");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e, nullptr);
 }
 
 TEST_F(ParserImplTest, Statement_Return_NoValue) {
-  ParserImpl p{"return;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("return;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsReturn());
@@ -50,9 +49,9 @@
 }
 
 TEST_F(ParserImplTest, Statement_Return_Value) {
-  ParserImpl p{"return a + b * (.1 - .2);"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("return a + b * (.1 - .2);");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsReturn());
@@ -62,227 +61,227 @@
 }
 
 TEST_F(ParserImplTest, Statement_Return_MissingSemi) {
-  ParserImpl p{"return"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("return");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:7: missing ;");
+  EXPECT_EQ(p->error(), "1:7: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_Return_Invalid) {
-  ParserImpl p{"return if(a) {};"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("return if(a) {};");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ;");
+  EXPECT_EQ(p->error(), "1:8: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_If) {
-  ParserImpl p{"if (a) {}"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("if (a) {}");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsIf());
 }
 
 TEST_F(ParserImplTest, Statement_If_Invalid) {
-  ParserImpl p{"if (a) { fn main() -> {}}"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("if (a) { fn main() -> {}}");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: missing }");
+  EXPECT_EQ(p->error(), "1:10: missing }");
 }
 
 TEST_F(ParserImplTest, Statement_Unless) {
-  ParserImpl p{"unless (a) {}"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("unless (a) {}");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnless());
 }
 
 TEST_F(ParserImplTest, Statement_Unless_Invalid) {
-  ParserImpl p{"unless () {}"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("unless () {}");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:9: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, Statement_Regardless) {
-  ParserImpl p{"regardless (a) {}"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("regardless (a) {}");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsRegardless());
 }
 
 TEST_F(ParserImplTest, Statement_Regardless_Invalid) {
-  ParserImpl p{"regardless () {}"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("regardless () {}");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:13: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, Statement_Variable) {
-  ParserImpl p{"var a : i32 = 1;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("var a : i32 = 1;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsVariable());
 }
 
 TEST_F(ParserImplTest, Statement_Variable_Invalid) {
-  ParserImpl p{"var a : i32 =;"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var a : i32 =;");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing initializer for variable declaration");
+  EXPECT_EQ(p->error(), "1:14: missing initializer for variable declaration");
 }
 
 TEST_F(ParserImplTest, Statement_Variable_MissingSemicolon) {
-  ParserImpl p{"var a : i32"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var a : i32");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: missing ;");
+  EXPECT_EQ(p->error(), "1:12: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_Switch) {
-  ParserImpl p{"switch (a) {}"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("switch (a) {}");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsSwitch());
 }
 
 TEST_F(ParserImplTest, Statement_Switch_Invalid) {
-  ParserImpl p{"switch (a) { case: {}}"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("switch (a) { case: {}}");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:18: unable to parse case conditional");
+  EXPECT_EQ(p->error(), "1:18: unable to parse case conditional");
 }
 
 TEST_F(ParserImplTest, Statement_Loop) {
-  ParserImpl p{"loop {}"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("loop {}");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsLoop());
 }
 
 TEST_F(ParserImplTest, Statement_Loop_Invalid) {
-  ParserImpl p{"loop kill; }"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("loop kill; }");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing { for loop");
+  EXPECT_EQ(p->error(), "1:6: missing { for loop");
 }
 
 TEST_F(ParserImplTest, Statement_Assignment) {
-  ParserImpl p{"a = b;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a = b;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   EXPECT_TRUE(e->IsAssign());
 }
 
 TEST_F(ParserImplTest, Statement_Assignment_Invalid) {
-  ParserImpl p{"a = if(b) {};"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a = if(b) {};");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: unable to parse right side of assignment");
+  EXPECT_EQ(p->error(), "1:5: unable to parse right side of assignment");
 }
 
 TEST_F(ParserImplTest, Statement_Assignment_MissingSemicolon) {
-  ParserImpl p{"a = b"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a = b");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ;");
+  EXPECT_EQ(p->error(), "1:6: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_Break) {
-  ParserImpl p{"break;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("break;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   EXPECT_TRUE(e->IsBreak());
 }
 
 TEST_F(ParserImplTest, Statement_Break_Invalid) {
-  ParserImpl p{"break if (a = b);"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("break if (a = b);");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: expected )");
+  EXPECT_EQ(p->error(), "1:13: expected )");
 }
 
 TEST_F(ParserImplTest, Statement_Break_MissingSemicolon) {
-  ParserImpl p{"break if (a == b)"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("break if (a == b)");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:18: missing ;");
+  EXPECT_EQ(p->error(), "1:18: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_Continue) {
-  ParserImpl p{"continue;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("continue;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   EXPECT_TRUE(e->IsContinue());
 }
 
 TEST_F(ParserImplTest, Statement_Continue_Invalid) {
-  ParserImpl p{"continue if (a = b);"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("continue if (a = b);");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:16: expected )");
+  EXPECT_EQ(p->error(), "1:16: expected )");
 }
 
 TEST_F(ParserImplTest, Statement_Continue_MissingSemicolon) {
-  ParserImpl p{"continue if (a == b)"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("continue if (a == b)");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:21: missing ;");
+  EXPECT_EQ(p->error(), "1:21: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_Kill) {
-  ParserImpl p{"kill;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("kill;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_NE(e, nullptr);
   ASSERT_TRUE(e->IsKill());
 }
 
 TEST_F(ParserImplTest, Statement_Kill_MissingSemicolon) {
-  ParserImpl p{"kill"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("kill");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing ;");
+  EXPECT_EQ(p->error(), "1:5: missing ;");
 }
 
 TEST_F(ParserImplTest, Statement_Nop) {
-  ParserImpl p{"nop;"};
-  auto e = p.statement();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("nop;");
+  auto e = p->statement();
+  ASSERT_FALSE(p->has_error()) << p->error();
   EXPECT_NE(e, nullptr);
   ASSERT_TRUE(e->IsNop());
 }
 
 TEST_F(ParserImplTest, Statement_Nop_MissingSemicolon) {
-  ParserImpl p{"nop"};
-  auto e = p.statement();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("nop");
+  auto e = p->statement();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:4: missing ;");
+  EXPECT_EQ(p->error(), "1:4: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_statements_test.cc b/src/reader/wgsl/parser_impl_statements_test.cc
index f993794..8249234 100644
--- a/src/reader/wgsl/parser_impl_statements_test.cc
+++ b/src/reader/wgsl/parser_impl_statements_test.cc
@@ -15,17 +15,16 @@
 #include "gtest/gtest.h"
 #include "src/ast/statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, Statements) {
-  ParserImpl p{"nop; kill; return;"};
-  auto e = p.statements();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("nop; kill; return;");
+  auto e = p->statements();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 3);
   EXPECT_TRUE(e[0]->IsNop());
   EXPECT_TRUE(e[1]->IsKill());
@@ -33,9 +32,9 @@
 }
 
 TEST_F(ParserImplTest, Statements_Empty) {
-  ParserImpl p{""};
-  auto e = p.statements();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("");
+  auto e = p->statements();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_EQ(e.size(), 0);
 }
 
diff --git a/src/reader/wgsl/parser_impl_storage_class_test.cc b/src/reader/wgsl/parser_impl_storage_class_test.cc
index f479d00..7e233cb 100644
--- a/src/reader/wgsl/parser_impl_storage_class_test.cc
+++ b/src/reader/wgsl/parser_impl_storage_class_test.cc
@@ -15,12 +15,12 @@
 #include "gtest/gtest.h"
 #include "src/ast/storage_class.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
-
-using ParserImplTest = testing::Test;
+namespace {
 
 struct StorageClassData {
   const char* input;
@@ -30,16 +30,41 @@
   out << std::string(data.input);
   return out;
 }
-using StorageClassTest = testing::TestWithParam<StorageClassData>;
+
+class StorageClassTest : public testing::TestWithParam<StorageClassData> {
+ public:
+  StorageClassTest() = default;
+  ~StorageClassTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace
+
 TEST_P(StorageClassTest, Parses) {
   auto params = GetParam();
-  ParserImpl p{params.input};
+  auto p = parser(params.input);
 
-  auto sc = p.storage_class();
-  ASSERT_FALSE(p.has_error());
+  auto sc = p->storage_class();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(sc, params.result);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsEof());
 }
 INSTANTIATE_TEST_SUITE_P(
@@ -59,11 +84,11 @@
         StorageClassData{"function", ast::StorageClass::kFunction}));
 
 TEST_F(ParserImplTest, StorageClass_NoMatch) {
-  ParserImpl p{"not-a-storage-class"};
-  auto sc = p.storage_class();
+  auto p = parser("not-a-storage-class");
+  auto sc = p->storage_class();
   ASSERT_EQ(sc, ast::StorageClass::kNone);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsIdentifier());
   EXPECT_EQ(t.to_str(), "not");
 }
diff --git a/src/reader/wgsl/parser_impl_struct_body_decl_test.cc b/src/reader/wgsl/parser_impl_struct_body_decl_test.cc
index 62c4f57..e2f1cc5 100644
--- a/src/reader/wgsl/parser_impl_struct_body_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_body_decl_test.cc
@@ -15,64 +15,60 @@
 #include "gtest/gtest.h"
 #include "src/ast/type/i32_type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, StructBodyDecl_Parses) {
-  auto i32 =
-      TypeManager::Instance()->Get(std::make_unique<ast::type::I32Type>());
+  auto i32 = tm()->Get(std::make_unique<ast::type::I32Type>());
 
-  ParserImpl p{"{a : i32;}"};
-  auto m = p.struct_body_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("{a : i32;}");
+  auto m = p->struct_body_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(m.size(), 1);
 
   const auto& mem = m[0];
   EXPECT_EQ(mem->name(), "a");
   EXPECT_EQ(mem->type(), i32);
   EXPECT_EQ(mem->decorations().size(), 0);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, StructBodyDecl_ParsesEmpty) {
-  ParserImpl p{"{}"};
-  auto m = p.struct_body_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("{}");
+  auto m = p->struct_body_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(m.size(), 0);
 }
 
 TEST_F(ParserImplTest, StructBodyDecl_InvalidMember) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
 {
   [[offset nan]] a : i32;
-})"};
-  auto m = p.struct_body_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "3:12: invalid value for offset decoration");
+})");
+  auto m = p->struct_body_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "3:12: invalid value for offset decoration");
 }
 
 TEST_F(ParserImplTest, StructBodyDecl_MissingClosingBracket) {
-  ParserImpl p{"{a : i32;"};
-  auto m = p.struct_body_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:10: missing } for struct declaration");
+  auto p = parser("{a : i32;");
+  auto m = p->struct_body_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:10: missing } for struct declaration");
 }
 
 TEST_F(ParserImplTest, StructBodyDecl_InvalidToken) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
 {
   a : i32;
   1.23
-} )"};
-  auto m = p.struct_body_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "4:3: invalid identifier declaration");
+} )");
+  auto m = p->struct_body_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "4:3: invalid identifier declaration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_struct_decl_test.cc b/src/reader/wgsl/parser_impl_struct_decl_test.cc
index 87e98cb..1770384 100644
--- a/src/reader/wgsl/parser_impl_struct_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_decl_test.cc
@@ -15,21 +15,20 @@
 #include "gtest/gtest.h"
 #include "src/ast/type/struct_type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, StructDecl_Parses) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
 struct {
   a : i32;
   [[offset 4 ]] b : f32;
-})"};
-  auto s = p.struct_decl();
-  ASSERT_FALSE(p.has_error());
+})");
+  auto s = p->struct_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(s, nullptr);
   ASSERT_EQ(s->impl()->members().size(), 2);
   EXPECT_EQ(s->impl()->members()[0]->name(), "a");
@@ -37,13 +36,13 @@
 }
 
 TEST_F(ParserImplTest, StructDecl_ParsesWithDecoration) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
 [[block]] struct {
   a : f32;
   b : f32;
-})"};
-  auto s = p.struct_decl();
-  ASSERT_FALSE(p.has_error());
+})");
+  auto s = p->struct_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(s, nullptr);
   ASSERT_EQ(s->impl()->members().size(), 2);
   EXPECT_EQ(s->impl()->members()[0]->name(), "a");
@@ -51,43 +50,43 @@
 }
 
 TEST_F(ParserImplTest, StructDecl_EmptyMembers) {
-  ParserImpl p{"struct {}"};
-  auto s = p.struct_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("struct {}");
+  auto s = p->struct_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(s, nullptr);
   ASSERT_EQ(s->impl()->members().size(), 0);
 }
 
 TEST_F(ParserImplTest, StructDecl_MissingBracketLeft) {
-  ParserImpl p{"struct }"};
-  auto s = p.struct_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("struct }");
+  auto s = p->struct_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(s, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing { for struct declaration");
+  EXPECT_EQ(p->error(), "1:8: missing { for struct declaration");
 }
 
 TEST_F(ParserImplTest, StructDecl_InvalidStructBody) {
-  ParserImpl p{"struct { a : B; }"};
-  auto s = p.struct_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("struct { a : B; }");
+  auto s = p->struct_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(s, nullptr);
-  EXPECT_EQ(p.error(), "1:14: unknown type alias 'B'");
+  EXPECT_EQ(p->error(), "1:14: unknown type alias 'B'");
 }
 
 TEST_F(ParserImplTest, StructDecl_InvalidStructDecorationDecl) {
-  ParserImpl p{"[[block struct { a : i32; }"};
-  auto s = p.struct_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("[[block struct { a : i32; }");
+  auto s = p->struct_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(s, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing ]] for struct decoration");
+  EXPECT_EQ(p->error(), "1:9: missing ]] for struct decoration");
 }
 
 TEST_F(ParserImplTest, StructDecl_MissingStruct) {
-  ParserImpl p{"[[block]] {}"};
-  auto s = p.struct_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("[[block]] {}");
+  auto s = p->struct_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(s, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing struct declaration");
+  EXPECT_EQ(p->error(), "1:11: missing struct declaration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_struct_decoration_decl_test.cc b/src/reader/wgsl/parser_impl_struct_decoration_decl_test.cc
index d6e1cc4..3af41dd 100644
--- a/src/reader/wgsl/parser_impl_struct_decoration_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_decoration_decl_test.cc
@@ -14,32 +14,31 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, StructDecorationDecl_Parses) {
-  ParserImpl p{"[[block]]"};
-  auto d = p.struct_decoration_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("[[block]]");
+  auto d = p->struct_decoration_decl();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(d, ast::StructDecoration::kBlock);
 }
 
 TEST_F(ParserImplTest, StructDecorationDecl_MissingAttrRight) {
-  ParserImpl p{"[[block"};
-  p.struct_decoration_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: missing ]] for struct decoration");
+  auto p = parser("[[block");
+  p->struct_decoration_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: missing ]] for struct decoration");
 }
 
 TEST_F(ParserImplTest, StructDecorationDecl_InvalidDecoration) {
-  ParserImpl p{"[[invalid]]"};
-  p.struct_decoration_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:3: unknown struct decoration");
+  auto p = parser("[[invalid]]");
+  p->struct_decoration_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:3: unknown struct decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_struct_decoration_test.cc b/src/reader/wgsl/parser_impl_struct_decoration_test.cc
index 3f5aec3..d8fa675 100644
--- a/src/reader/wgsl/parser_impl_struct_decoration_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_decoration_test.cc
@@ -15,12 +15,12 @@
 #include "gtest/gtest.h"
 #include "src/ast/struct_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
-
-using ParserImplTest = testing::Test;
+namespace {
 
 struct StructDecorationData {
   const char* input;
@@ -30,16 +30,42 @@
   out << std::string(data.input);
   return out;
 }
-using StructDecorationTest = testing::TestWithParam<StructDecorationData>;
+
+class StructDecorationTest
+    : public testing::TestWithParam<StructDecorationData> {
+ public:
+  StructDecorationTest() = default;
+  ~StructDecorationTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace
+
 TEST_P(StructDecorationTest, Parses) {
   auto params = GetParam();
-  ParserImpl p{params.input};
+  auto p = parser(params.input);
 
-  auto deco = p.struct_decoration();
-  ASSERT_FALSE(p.has_error());
+  auto deco = p->struct_decoration();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(deco, params.result);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsEof());
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
@@ -48,11 +74,11 @@
                              "block", ast::StructDecoration::kBlock}));
 
 TEST_F(ParserImplTest, StructDecoration_NoMatch) {
-  ParserImpl p{"not-a-stage"};
-  auto deco = p.struct_decoration();
+  auto p = parser("not-a-stage");
+  auto deco = p->struct_decoration();
   ASSERT_EQ(deco, ast::StructDecoration::kNone);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsIdentifier());
   EXPECT_EQ(t.to_str(), "not");
 }
diff --git a/src/reader/wgsl/parser_impl_struct_member_decoration_decl_test.cc b/src/reader/wgsl/parser_impl_struct_member_decoration_decl_test.cc
index 3e8069d..7aed2c3 100644
--- a/src/reader/wgsl/parser_impl_struct_member_decoration_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_member_decoration_decl_test.cc
@@ -15,54 +15,53 @@
 #include "gtest/gtest.h"
 #include "src/ast/struct_member_offset_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, StructMemberDecorationDecl_EmptyStr) {
-  ParserImpl p{""};
-  auto deco = p.struct_member_decoration_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("");
+  auto deco = p->struct_member_decoration_decl();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(deco.size(), 0);
 }
 
 TEST_F(ParserImplTest, StructMemberDecorationDecl_EmptyBlock) {
-  ParserImpl p{"[[]]"};
-  auto deco = p.struct_member_decoration_decl();
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:3: empty struct member decoration found");
+  auto p = parser("[[]]");
+  auto deco = p->struct_member_decoration_decl();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:3: empty struct member decoration found");
 }
 
 TEST_F(ParserImplTest, StructMemberDecorationDecl_Single) {
-  ParserImpl p{"[[offset 4]]"};
-  auto deco = p.struct_member_decoration_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("[[offset 4]]");
+  auto deco = p->struct_member_decoration_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(deco.size(), 1);
   EXPECT_TRUE(deco[0]->IsOffset());
 }
 
 TEST_F(ParserImplTest, StructMemberDecorationDecl_HandlesDuplicate) {
-  ParserImpl p{"[[offset 2, offset 4]]"};
-  auto deco = p.struct_member_decoration_decl();
-  ASSERT_TRUE(p.has_error()) << p.error();
-  EXPECT_EQ(p.error(), "1:21: duplicate offset decoration found");
+  auto p = parser("[[offset 2, offset 4]]");
+  auto deco = p->struct_member_decoration_decl();
+  ASSERT_TRUE(p->has_error()) << p->error();
+  EXPECT_EQ(p->error(), "1:21: duplicate offset decoration found");
 }
 
 TEST_F(ParserImplTest, StructMemberDecorationDecl_InvalidDecoration) {
-  ParserImpl p{"[[offset nan]]"};
-  auto deco = p.struct_member_decoration_decl();
-  ASSERT_TRUE(p.has_error()) << p.error();
-  EXPECT_EQ(p.error(), "1:10: invalid value for offset decoration");
+  auto p = parser("[[offset nan]]");
+  auto deco = p->struct_member_decoration_decl();
+  ASSERT_TRUE(p->has_error()) << p->error();
+  EXPECT_EQ(p->error(), "1:10: invalid value for offset decoration");
 }
 
 TEST_F(ParserImplTest, StructMemberDecorationDecl_MissingClose) {
-  ParserImpl p{"[[offset 4"};
-  auto deco = p.struct_member_decoration_decl();
-  ASSERT_TRUE(p.has_error()) << p.error();
-  EXPECT_EQ(p.error(), "1:11: missing ]] for struct member decoration");
+  auto p = parser("[[offset 4");
+  auto deco = p->struct_member_decoration_decl();
+  ASSERT_TRUE(p->has_error()) << p->error();
+  EXPECT_EQ(p->error(), "1:11: missing ]] for struct member decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_struct_member_decoration_test.cc b/src/reader/wgsl/parser_impl_struct_member_decoration_test.cc
index 14a760c..9f11c43 100644
--- a/src/reader/wgsl/parser_impl_struct_member_decoration_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_member_decoration_test.cc
@@ -15,18 +15,17 @@
 #include "gtest/gtest.h"
 #include "src/ast/struct_member_offset_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, StructMemberDecoration_Offset) {
-  ParserImpl p{"offset 4"};
-  auto deco = p.struct_member_decoration();
+  auto p = parser("offset 4");
+  auto deco = p->struct_member_decoration();
   ASSERT_NE(deco, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(deco->IsOffset());
 
   auto o = deco->AsOffset();
@@ -34,19 +33,19 @@
 }
 
 TEST_F(ParserImplTest, StructMemberDecoration_Offset_MissingValue) {
-  ParserImpl p{"offset"};
-  auto deco = p.struct_member_decoration();
+  auto p = parser("offset");
+  auto deco = p->struct_member_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:7: invalid value for offset decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:7: invalid value for offset decoration");
 }
 
 TEST_F(ParserImplTest, StructMemberDecoration_Offset_MissingInvalid) {
-  ParserImpl p{"offset nan"};
-  auto deco = p.struct_member_decoration();
+  auto p = parser("offset nan");
+  auto deco = p->struct_member_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: invalid value for offset decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: invalid value for offset decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_struct_member_test.cc b/src/reader/wgsl/parser_impl_struct_member_test.cc
index ee524b3..3e1c9af 100644
--- a/src/reader/wgsl/parser_impl_struct_member_test.cc
+++ b/src/reader/wgsl/parser_impl_struct_member_test.cc
@@ -16,37 +16,32 @@
 #include "src/ast/struct_member_offset_decoration.h"
 #include "src/ast/type/i32_type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, StructMember_Parses) {
-  auto i32 =
-      TypeManager::Instance()->Get(std::make_unique<ast::type::I32Type>());
+  auto i32 = tm()->Get(std::make_unique<ast::type::I32Type>());
 
-  ParserImpl p{"a : i32;"};
-  auto m = p.struct_member();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("a : i32;");
+  auto m = p->struct_member();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(m, nullptr);
 
   EXPECT_EQ(m->name(), "a");
   EXPECT_EQ(m->type(), i32);
   EXPECT_EQ(m->decorations().size(), 0);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, StructMember_ParsesWithDecoration) {
-  auto i32 =
-      TypeManager::Instance()->Get(std::make_unique<ast::type::I32Type>());
+  auto i32 = tm()->Get(std::make_unique<ast::type::I32Type>());
 
-  ParserImpl p{"[[offset 2]] a : i32;"};
-  auto m = p.struct_member();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("[[offset 2]] a : i32;");
+  auto m = p->struct_member();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(m, nullptr);
 
   EXPECT_EQ(m->name(), "a");
@@ -54,32 +49,30 @@
   EXPECT_EQ(m->decorations().size(), 1);
   EXPECT_TRUE(m->decorations()[0]->IsOffset());
   EXPECT_EQ(m->decorations()[0]->AsOffset()->offset(), 2);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, StructMember_InvalidDecoration) {
-  ParserImpl p{"[[offset nan]] a : i32;"};
-  auto m = p.struct_member();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("[[offset nan]] a : i32;");
+  auto m = p->struct_member();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(m, nullptr);
-  EXPECT_EQ(p.error(), "1:10: invalid value for offset decoration");
+  EXPECT_EQ(p->error(), "1:10: invalid value for offset decoration");
 }
 
 TEST_F(ParserImplTest, StructMember_InvalidVariable) {
-  ParserImpl p{"[[offset 4]] a : B;"};
-  auto m = p.struct_member();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("[[offset 4]] a : B;");
+  auto m = p->struct_member();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(m, nullptr);
-  EXPECT_EQ(p.error(), "1:18: unknown type alias 'B'");
+  EXPECT_EQ(p->error(), "1:18: unknown type alias 'B'");
 }
 
 TEST_F(ParserImplTest, StructMember_MissingSemicolon) {
-  ParserImpl p{"a : i32"};
-  auto m = p.struct_member();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("a : i32");
+  auto m = p->struct_member();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(m, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ; for struct member");
+  EXPECT_EQ(p->error(), "1:8: missing ; for struct member");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_switch_body_test.cc b/src/reader/wgsl/parser_impl_switch_body_test.cc
index d155ac7..fdd4fbb 100644
--- a/src/reader/wgsl/parser_impl_switch_body_test.cc
+++ b/src/reader/wgsl/parser_impl_switch_body_test.cc
@@ -15,17 +15,16 @@
 #include "gtest/gtest.h"
 #include "src/ast/case_statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, SwitchBody_Case) {
-  ParserImpl p{"case 1: { a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("case 1: { a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsCase());
   EXPECT_FALSE(e->IsDefault());
@@ -34,57 +33,57 @@
 }
 
 TEST_F(ParserImplTest, SwitchBody_Case_InvalidConstLiteral) {
-  ParserImpl p{"case a == 4: { a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("case a == 4: { a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unable to parse case conditional");
+  EXPECT_EQ(p->error(), "1:6: unable to parse case conditional");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Case_MissingConstLiteral) {
-  ParserImpl p{"case: { a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("case: { a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: unable to parse case conditional");
+  EXPECT_EQ(p->error(), "1:5: unable to parse case conditional");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Case_MissingColon) {
-  ParserImpl p{"case 1 { a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("case 1 { a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing : for case statement");
+  EXPECT_EQ(p->error(), "1:8: missing : for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Case_MissingBracketLeft) {
-  ParserImpl p{"case 1: a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("case 1: a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing { for case statement");
+  EXPECT_EQ(p->error(), "1:9: missing { for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Case_MissingBracketRight) {
-  ParserImpl p{"case 1: { a = 4; "};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("case 1: { a = 4; ");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:18: missing } for case statement");
+  EXPECT_EQ(p->error(), "1:18: missing } for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Case_InvalidCaseBody) {
-  ParserImpl p{"case 1: { fn main() -> void {} }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("case 1: { fn main() -> void {} }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing } for case statement");
+  EXPECT_EQ(p->error(), "1:11: missing } for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Default) {
-  ParserImpl p{"default: { a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("default: { a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsCase());
   EXPECT_TRUE(e->IsDefault());
@@ -93,35 +92,35 @@
 }
 
 TEST_F(ParserImplTest, SwitchBody_Default_MissingColon) {
-  ParserImpl p{"default { a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("default { a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing : for case statement");
+  EXPECT_EQ(p->error(), "1:9: missing : for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Default_MissingBracketLeft) {
-  ParserImpl p{"default: a = 4; }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("default: a = 4; }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:10: missing { for case statement");
+  EXPECT_EQ(p->error(), "1:10: missing { for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Default_MissingBracketRight) {
-  ParserImpl p{"default: { a = 4; "};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("default: { a = 4; ");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:19: missing } for case statement");
+  EXPECT_EQ(p->error(), "1:19: missing } for case statement");
 }
 
 TEST_F(ParserImplTest, SwitchBody_Default_InvalidCaseBody) {
-  ParserImpl p{"default: { fn main() -> void {} }"};
-  auto e = p.switch_body();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("default: { fn main() -> void {} }");
+  auto e = p->switch_body();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: missing } for case statement");
+  EXPECT_EQ(p->error(), "1:12: missing } for case statement");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_switch_stmt_test.cc b/src/reader/wgsl/parser_impl_switch_stmt_test.cc
index 8016ec5..36da865 100644
--- a/src/reader/wgsl/parser_impl_switch_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_switch_stmt_test.cc
@@ -16,20 +16,19 @@
 #include "src/ast/case_statement.h"
 #include "src/ast/switch_statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, SwitchStmt_WithoutDefault) {
-  ParserImpl p{R"(switch(a) {
+  auto p = parser(R"(switch(a) {
   case 1: {}
   case 2: {}
-})"};
-  auto e = p.switch_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+})");
+  auto e = p->switch_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsSwitch());
   ASSERT_EQ(e->body().size(), 2);
@@ -38,22 +37,22 @@
 }
 
 TEST_F(ParserImplTest, SwitchStmt_Empty) {
-  ParserImpl p{"switch(a) { }"};
-  auto e = p.switch_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("switch(a) { }");
+  auto e = p->switch_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsSwitch());
   ASSERT_EQ(e->body().size(), 0);
 }
 
 TEST_F(ParserImplTest, SwitchStmt_DefaultInMiddle) {
-  ParserImpl p{R"(switch(a) {
+  auto p = parser(R"(switch(a) {
   case 1: {}
   default: {}
   case 2: {}
-})"};
-  auto e = p.switch_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+})");
+  auto e = p->switch_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsSwitch());
 
@@ -64,45 +63,45 @@
 }
 
 TEST_F(ParserImplTest, SwitchStmt_InvalidExpression) {
-  ParserImpl p{"switch(a=b) {}"};
-  auto e = p.switch_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("switch(a=b) {}");
+  auto e = p->switch_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: expected )");
+  EXPECT_EQ(p->error(), "1:9: expected )");
 }
 
 TEST_F(ParserImplTest, SwitchStmt_MissingExpression) {
-  ParserImpl p{"switch {}"};
-  auto e = p.switch_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("switch {}");
+  auto e = p->switch_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: expected (");
+  EXPECT_EQ(p->error(), "1:8: expected (");
 }
 
 TEST_F(ParserImplTest, SwitchStmt_MissingBracketLeft) {
-  ParserImpl p{"switch(a) }"};
-  auto e = p.switch_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("switch(a) }");
+  auto e = p->switch_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing { for switch statement");
+  EXPECT_EQ(p->error(), "1:11: missing { for switch statement");
 }
 
 TEST_F(ParserImplTest, SwitchStmt_MissingBracketRight) {
-  ParserImpl p{"switch(a) {"};
-  auto e = p.switch_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("switch(a) {");
+  auto e = p->switch_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: missing } for switch statement");
+  EXPECT_EQ(p->error(), "1:12: missing } for switch statement");
 }
 
 TEST_F(ParserImplTest, SwitchStmt_InvalidBody) {
-  ParserImpl p{R"(switch(a) {
+  auto p = parser(R"(switch(a) {
   case: {}
-})"};
-  auto e = p.switch_stmt();
-  ASSERT_TRUE(p.has_error());
+})");
+  auto e = p->switch_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "2:7: unable to parse case conditional");
+  EXPECT_EQ(p->error(), "2:7: unable to parse case conditional");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_test.cc b/src/reader/wgsl/parser_impl_test.cc
index d59d5d4..d2c18cc 100644
--- a/src/reader/wgsl/parser_impl_test.cc
+++ b/src/reader/wgsl/parser_impl_test.cc
@@ -16,20 +16,19 @@
 
 #include "gtest/gtest.h"
 #include "src/ast/type/i32_type.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, Empty) {
-  ParserImpl p{""};
-  ASSERT_TRUE(p.Parse()) << p.error();
+  auto p = parser("");
+  ASSERT_TRUE(p->Parse()) << p->error();
 }
 
 TEST_F(ParserImplTest, DISABLED_Parses) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
 import "GLSL.std.430" as glsl;
 
 [[location 0]] var<out> gl_FragColor : vec4<f32>;
@@ -37,41 +36,41 @@
 fn main() -> void {
   gl_FragColor = vec4<f32>(.4, .2, .3, 1);
 }
-)"};
-  ASSERT_TRUE(p.Parse()) << p.error();
+)");
+  ASSERT_TRUE(p->Parse()) << p->error();
 
-  auto m = p.module();
+  auto m = p->module();
   ASSERT_EQ(1, m.imports().size());
 
   // TODO(dsinclair) check rest of AST ...
 }
 
 TEST_F(ParserImplTest, DISABLED_HandlesError) {
-  ParserImpl p{R"(
+  auto p = parser(R"(
 import "GLSL.std.430" as glsl;
 
 fn main() ->  {  # missing return type
   return;
-})"};
+})");
 
-  ASSERT_FALSE(p.Parse());
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "4:15: missing return type for function");
+  ASSERT_FALSE(p->Parse());
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "4:15: missing return type for function");
 }
 
 TEST_F(ParserImplTest, GetRegisteredType) {
-  ParserImpl p{""};
+  auto p = parser("");
   ast::type::I32Type i32;
-  p.register_alias("my_alias", &i32);
+  p->register_alias("my_alias", &i32);
 
-  auto alias = p.get_alias("my_alias");
+  auto alias = p->get_alias("my_alias");
   ASSERT_NE(alias, nullptr);
   ASSERT_EQ(alias, &i32);
 }
 
 TEST_F(ParserImplTest, GetUnregisteredType) {
-  ParserImpl p{""};
-  auto alias = p.get_alias("my_alias");
+  auto p = parser("");
+  auto alias = p->get_alias("my_alias");
   ASSERT_EQ(alias, nullptr);
 }
 
diff --git a/src/reader/wgsl/parser_impl_test_helper.h b/src/reader/wgsl/parser_impl_test_helper.h
new file mode 100644
index 0000000..a0d2033
--- /dev/null
+++ b/src/reader/wgsl/parser_impl_test_helper.h
@@ -0,0 +1,58 @@
+// Copyright 2020 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef SRC_READER_WGSL_PARSER_IMPL_TEST_HELPER_H_
+#define SRC_READER_WGSL_PARSER_IMPL_TEST_HELPER_H_
+
+#include <memory>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "src/context.h"
+#include "src/reader/wgsl/parser_impl.h"
+
+namespace tint {
+namespace reader {
+namespace wgsl {
+
+class ParserImplTest : public testing::Test {
+ public:
+  ParserImplTest() = default;
+  ~ParserImplTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+  TypeManager* tm() { return &tm_; }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace wgsl
+}  // namespace reader
+}  // namespace tint
+
+#endif  // SRC_READER_WGSL_PARSER_IMPL_TEST_HELPER_H_
diff --git a/src/reader/wgsl/parser_impl_type_alias_test.cc b/src/reader/wgsl/parser_impl_type_alias_test.cc
index b4f814c..28ab134 100644
--- a/src/reader/wgsl/parser_impl_type_alias_test.cc
+++ b/src/reader/wgsl/parser_impl_type_alias_test.cc
@@ -17,32 +17,28 @@
 #include "src/ast/type/i32_type.h"
 #include "src/ast/type/struct_type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, TypeDecl_ParsesType) {
-  auto tm = TypeManager::Instance();
-  auto i32 = tm->Get(std::make_unique<ast::type::I32Type>());
+  auto i32 = tm()->Get(std::make_unique<ast::type::I32Type>());
 
-  ParserImpl p{"type a = i32"};
-  auto t = p.type_alias();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("type a = i32");
+  auto t = p->type_alias();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->type()->IsI32());
   ASSERT_EQ(t->type(), i32);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, TypeDecl_ParsesStruct) {
-  ParserImpl p{"type a = struct { b: i32; c: f32;}"};
-  auto t = p.type_alias();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("type a = struct { b: i32; c: f32;}");
+  auto t = p->type_alias();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(t, nullptr);
   EXPECT_EQ(t->name(), "a");
   ASSERT_TRUE(t->type()->IsStruct());
@@ -52,43 +48,43 @@
 }
 
 TEST_F(ParserImplTest, TypeDecl_MissingIdent) {
-  ParserImpl p{"type = i32"};
-  auto t = p.type_alias();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("type = i32");
+  auto t = p->type_alias();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(t, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing identifier for type alias");
+  EXPECT_EQ(p->error(), "1:6: missing identifier for type alias");
 }
 
 TEST_F(ParserImplTest, TypeDecl_InvalidIdent) {
-  ParserImpl p{"type 123 = i32"};
-  auto t = p.type_alias();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("type 123 = i32");
+  auto t = p->type_alias();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(t, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing identifier for type alias");
+  EXPECT_EQ(p->error(), "1:6: missing identifier for type alias");
 }
 
 TEST_F(ParserImplTest, TypeDecl_MissingEqual) {
-  ParserImpl p{"type a i32"};
-  auto t = p.type_alias();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("type a i32");
+  auto t = p->type_alias();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(t, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing = for type alias");
+  EXPECT_EQ(p->error(), "1:8: missing = for type alias");
 }
 
 TEST_F(ParserImplTest, TypeDecl_InvalidType) {
-  ParserImpl p{"type a = B"};
-  auto t = p.type_alias();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("type a = B");
+  auto t = p->type_alias();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(t, nullptr);
-  EXPECT_EQ(p.error(), "1:10: unknown type alias 'B'");
+  EXPECT_EQ(p->error(), "1:10: unknown type alias 'B'");
 }
 
 TEST_F(ParserImplTest, TypeDecl_InvalidStruct) {
-  ParserImpl p{"type a = [[block]] {}"};
-  auto t = p.type_alias();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("type a = [[block]] {}");
+  auto t = p->type_alias();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(t, nullptr);
-  EXPECT_EQ(p.error(), "1:20: missing struct declaration");
+  EXPECT_EQ(p->error(), "1:20: missing struct declaration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_type_decl_test.cc b/src/reader/wgsl/parser_impl_type_decl_test.cc
index fcf07d7..24be1b5 100644
--- a/src/reader/wgsl/parser_impl_type_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_type_decl_test.cc
@@ -24,33 +24,31 @@
 #include "src/ast/type/u32_type.h"
 #include "src/ast/type/vector_type.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 #include "src/type_manager.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, TypeDecl_Invalid) {
-  ParserImpl p{"1234"};
-  auto t = p.type_decl();
+  auto p = parser("1234");
+  auto t = p->type_decl();
   EXPECT_EQ(t, nullptr);
-  EXPECT_FALSE(p.has_error());
+  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TypeDecl_Identifier) {
-  ParserImpl p{"A"};
+  auto p = parser("A");
 
-  auto tm = TypeManager::Instance();
-  auto int_type = tm->Get(std::make_unique<ast::type::I32Type>());
+  auto int_type = tm()->Get(std::make_unique<ast::type::I32Type>());
   // Pre-register to make sure that it's the same type.
   auto alias_type =
-      tm->Get(std::make_unique<ast::type::AliasType>("A", int_type));
+      tm()->Get(std::make_unique<ast::type::AliasType>("A", int_type));
 
-  p.register_alias("A", alias_type);
+  p->register_alias("A", alias_type);
 
-  auto t = p.type_decl();
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
   EXPECT_EQ(t, alias_type);
   ASSERT_TRUE(t->IsAlias());
@@ -58,73 +56,59 @@
   auto alias = t->AsAlias();
   EXPECT_EQ(alias->name(), "A");
   EXPECT_EQ(alias->type(), int_type);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, TypeDecl_Identifier_NotFound) {
-  ParserImpl p{"B"};
+  auto p = parser("B");
 
-  auto t = p.type_decl();
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  EXPECT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:1: unknown type alias 'B'");
+  EXPECT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:1: unknown type alias 'B'");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Bool) {
-  ParserImpl p{"bool"};
+  auto p = parser("bool");
 
-  auto tm = TypeManager::Instance();
-  auto bool_type = tm->Get(std::make_unique<ast::type::BoolType>());
+  auto bool_type = tm()->Get(std::make_unique<ast::type::BoolType>());
 
-  auto t = p.type_decl();
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
   EXPECT_EQ(t, bool_type);
   ASSERT_TRUE(t->IsBool());
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, TypeDecl_F32) {
-  ParserImpl p{"f32"};
+  auto p = parser("f32");
 
-  auto tm = TypeManager::Instance();
-  auto float_type = tm->Get(std::make_unique<ast::type::F32Type>());
+  auto float_type = tm()->Get(std::make_unique<ast::type::F32Type>());
 
-  auto t = p.type_decl();
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
   EXPECT_EQ(t, float_type);
   ASSERT_TRUE(t->IsF32());
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, TypeDecl_I32) {
-  ParserImpl p{"i32"};
+  auto p = parser("i32");
 
-  auto tm = TypeManager::Instance();
-  auto int_type = tm->Get(std::make_unique<ast::type::I32Type>());
+  auto int_type = tm()->Get(std::make_unique<ast::type::I32Type>());
 
-  auto t = p.type_decl();
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
   EXPECT_EQ(t, int_type);
   ASSERT_TRUE(t->IsI32());
-
-  TypeManager::Destroy();
 }
 
 TEST_F(ParserImplTest, TypeDecl_U32) {
-  ParserImpl p{"u32"};
+  auto p = parser("u32");
 
-  auto tm = TypeManager::Instance();
-  auto uint_type = tm->Get(std::make_unique<ast::type::U32Type>());
+  auto uint_type = tm()->Get(std::make_unique<ast::type::U32Type>());
 
-  auto t = p.type_decl();
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
   EXPECT_EQ(t, uint_type);
   ASSERT_TRUE(t->IsU32());
-
-  TypeManager::Destroy();
 }
 
 struct VecData {
@@ -135,13 +119,35 @@
   out << std::string(data.input);
   return out;
 }
-using VecTest = testing::TestWithParam<VecData>;
+class VecTest : public testing::TestWithParam<VecData> {
+ public:
+  VecTest() = default;
+  ~VecTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
 TEST_P(VecTest, Parse) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   EXPECT_TRUE(t->IsVector());
   EXPECT_EQ(t->AsVector()->size(), params.count);
 }
@@ -151,14 +157,36 @@
                                          VecData{"vec3<f32>", 3},
                                          VecData{"vec4<f32>", 4}));
 
-using VecMissingGreaterThanTest = testing::TestWithParam<VecData>;
+class VecMissingGreaterThanTest : public testing::TestWithParam<VecData> {
+ public:
+  VecMissingGreaterThanTest() = default;
+  ~VecMissingGreaterThanTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
 TEST_P(VecMissingGreaterThanTest, Handles_Missing_GreaterThan) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:9: missing > for vector");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:9: missing > for vector");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          VecMissingGreaterThanTest,
@@ -166,14 +194,36 @@
                                          VecData{"vec3<f32", 3},
                                          VecData{"vec4<f32", 4}));
 
-using VecMissingLessThanTest = testing::TestWithParam<VecData>;
+class VecMissingLessThanTest : public testing::TestWithParam<VecData> {
+ public:
+  VecMissingLessThanTest() = default;
+  ~VecMissingLessThanTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
 TEST_P(VecMissingLessThanTest, Handles_Missing_GreaterThan) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:5: missing < for vector");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:5: missing < for vector");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          VecMissingLessThanTest,
@@ -181,14 +231,36 @@
                                          VecData{"vec3", 3},
                                          VecData{"vec4", 4}));
 
-using VecBadType = testing::TestWithParam<VecData>;
+class VecBadType : public testing::TestWithParam<VecData> {
+ public:
+  VecBadType() = default;
+  ~VecBadType() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
 TEST_P(VecBadType, Handles_Unknown_Type) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:6: unknown type alias 'unknown'");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:6: unknown type alias 'unknown'");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          VecBadType,
@@ -196,14 +268,36 @@
                                          VecData{"vec3<unknown", 3},
                                          VecData{"vec4<unknown", 4}));
 
-using VecMissingType = testing::TestWithParam<VecData>;
+class VecMissingType : public testing::TestWithParam<VecData> {
+ public:
+  VecMissingType() = default;
+  ~VecMissingType() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
 TEST_P(VecMissingType, Handles_Missing_Type) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:6: unable to determine subtype for vector");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:6: unable to determine subtype for vector");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          VecMissingType,
@@ -212,10 +306,10 @@
                                          VecData{"vec4<>", 4}));
 
 TEST_F(ParserImplTest, TypeDecl_Ptr) {
-  ParserImpl p{"ptr<function, f32>"};
-  auto t = p.type_decl();
-  ASSERT_NE(t, nullptr) << p.error();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("ptr<function, f32>");
+  auto t = p->type_decl();
+  ASSERT_NE(t, nullptr) << p->error();
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(t->IsPointer());
 
   auto ptr = t->AsPointer();
@@ -224,10 +318,10 @@
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_ToVec) {
-  ParserImpl p{"ptr<function, vec2<f32>>"};
-  auto t = p.type_decl();
-  ASSERT_NE(t, nullptr) << p.error();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("ptr<function, vec2<f32>>");
+  auto t = p->type_decl();
+  ASSERT_NE(t, nullptr) << p->error();
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(t->IsPointer());
 
   auto ptr = t->AsPointer();
@@ -240,74 +334,74 @@
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_MissingLessThan) {
-  ParserImpl p{"ptr private, f32>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr private, f32>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:5: missing < for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:5: missing < for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_MissingGreaterThan) {
-  ParserImpl p{"ptr<function, f32"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<function, f32");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:18: missing > for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:18: missing > for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_MissingComma) {
-  ParserImpl p{"ptr<function f32>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<function f32>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:14: missing , for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:14: missing , for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_MissingStorageClass) {
-  ParserImpl p{"ptr<, f32>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<, f32>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:5: missing storage class for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:5: missing storage class for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_MissingParams) {
-  ParserImpl p{"ptr<>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:5: missing storage class for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:5: missing storage class for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_MissingType) {
-  ParserImpl p{"ptr<function,>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<function,>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:14: missing type for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:14: missing type for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_BadStorageClass) {
-  ParserImpl p{"ptr<unknown, f32>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<unknown, f32>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:5: missing storage class for ptr declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:5: missing storage class for ptr declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Ptr_BadType) {
-  ParserImpl p{"ptr<function, unknown>"};
-  auto t = p.type_decl();
+  auto p = parser("ptr<function, unknown>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:15: unknown type alias 'unknown'");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:15: unknown type alias 'unknown'");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array) {
-  ParserImpl p{"array<f32, 5>"};
-  auto t = p.type_decl();
+  auto p = parser("array<f32, 5>");
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(t->IsArray());
 
   auto a = t->AsArray();
@@ -317,10 +411,10 @@
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_Runtime) {
-  ParserImpl p{"array<u32>"};
-  auto t = p.type_decl();
+  auto p = parser("array<u32>");
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(t->IsArray());
 
   auto a = t->AsArray();
@@ -329,59 +423,59 @@
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_BadType) {
-  ParserImpl p{"array<unknown, 3>"};
-  auto t = p.type_decl();
+  auto p = parser("array<unknown, 3>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:7: unknown type alias 'unknown'");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:7: unknown type alias 'unknown'");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_ZeroSize) {
-  ParserImpl p{"array<f32, 0>"};
-  auto t = p.type_decl();
+  auto p = parser("array<f32, 0>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:12: invalid size for array declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:12: invalid size for array declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_NegativeSize) {
-  ParserImpl p{"array<f32, -1>"};
-  auto t = p.type_decl();
+  auto p = parser("array<f32, -1>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:12: invalid size for array declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:12: invalid size for array declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_BadSize) {
-  ParserImpl p{"array<f32, invalid>"};
-  auto t = p.type_decl();
+  auto p = parser("array<f32, invalid>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:12: missing size of array declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:12: missing size of array declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_MissingLessThan) {
-  ParserImpl p{"array f32>"};
-  auto t = p.type_decl();
+  auto p = parser("array f32>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:7: missing < for array declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:7: missing < for array declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_MissingGreaterThan) {
-  ParserImpl p{"array<f32"};
-  auto t = p.type_decl();
+  auto p = parser("array<f32");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:10: missing > for array declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:10: missing > for array declaration");
 }
 
 TEST_F(ParserImplTest, TypeDecl_Array_MissingComma) {
-  ParserImpl p{"array<f32 3>"};
-  auto t = p.type_decl();
+  auto p = parser("array<f32 3>");
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:11: missing > for array declaration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:11: missing > for array declaration");
 }
 
 struct MatrixData {
@@ -393,13 +487,35 @@
   out << std::string(data.input);
   return out;
 }
-using MatrixTest = testing::TestWithParam<MatrixData>;
+class MatrixTest : public testing::TestWithParam<MatrixData> {
+ public:
+  MatrixTest() = default;
+  ~MatrixTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
 TEST_P(MatrixTest, Parse) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_NE(t, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   EXPECT_TRUE(t->IsMatrix());
   auto mat = t->AsMatrix();
   EXPECT_EQ(mat->rows(), params.rows);
@@ -417,14 +533,35 @@
                                          MatrixData{"mat4x3<f32>", 4, 3},
                                          MatrixData{"mat4x4<f32>", 4, 4}));
 
-using MatrixMissingGreaterThanTest = testing::TestWithParam<MatrixData>;
+class MatrixMissingGreaterThanTest : public testing::TestWithParam<MatrixData> {
+ public:
+  MatrixMissingGreaterThanTest() = default;
+  ~MatrixMissingGreaterThanTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
 TEST_P(MatrixMissingGreaterThanTest, Handles_Missing_GreaterThan) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:11: missing > for matrix");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:11: missing > for matrix");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          MatrixMissingGreaterThanTest,
@@ -438,14 +575,35 @@
                                          MatrixData{"mat4x3<f32", 4, 3},
                                          MatrixData{"mat4x4<f32", 4, 4}));
 
-using MatrixMissingLessThanTest = testing::TestWithParam<MatrixData>;
+class MatrixMissingLessThanTest : public testing::TestWithParam<MatrixData> {
+ public:
+  MatrixMissingLessThanTest() = default;
+  ~MatrixMissingLessThanTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
 TEST_P(MatrixMissingLessThanTest, Handles_Missing_GreaterThan) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:8: missing < for matrix");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:8: missing < for matrix");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          MatrixMissingLessThanTest,
@@ -459,14 +617,35 @@
                                          MatrixData{"mat4x3 f32>", 4, 3},
                                          MatrixData{"mat4x4 f32>", 4, 4}));
 
-using MatrixBadType = testing::TestWithParam<MatrixData>;
+class MatrixBadType : public testing::TestWithParam<MatrixData> {
+ public:
+  MatrixBadType() = default;
+  ~MatrixBadType() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
 TEST_P(MatrixBadType, Handles_Unknown_Type) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:8: unknown type alias 'unknown'");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:8: unknown type alias 'unknown'");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          MatrixBadType,
@@ -480,14 +659,35 @@
                                          MatrixData{"mat4x3<unknown>", 4, 3},
                                          MatrixData{"mat4x4<unknown>", 4, 4}));
 
-using MatrixMissingType = testing::TestWithParam<MatrixData>;
+class MatrixMissingType : public testing::TestWithParam<MatrixData> {
+ public:
+  MatrixMissingType() = default;
+  ~MatrixMissingType() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
 TEST_P(MatrixMissingType, Handles_Missing_Type) {
   auto params = GetParam();
-  ParserImpl p{params.input};
-  auto t = p.type_decl();
+  auto p = parser(params.input);
+  auto t = p->type_decl();
   ASSERT_EQ(t, nullptr);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:8: unable to determine subtype for matrix");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:8: unable to determine subtype for matrix");
 }
 INSTANTIATE_TEST_SUITE_P(ParserImplTest,
                          MatrixMissingType,
diff --git a/src/reader/wgsl/parser_impl_unary_expression_test.cc b/src/reader/wgsl/parser_impl_unary_expression_test.cc
index 48acd55..6141243 100644
--- a/src/reader/wgsl/parser_impl_unary_expression_test.cc
+++ b/src/reader/wgsl/parser_impl_unary_expression_test.cc
@@ -21,17 +21,16 @@
 #include "src/ast/unary_method_expression.h"
 #include "src/ast/unary_op_expression.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, UnaryExpression_Postix) {
-  ParserImpl p{"a[2]"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("a[2]");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
 
   ASSERT_TRUE(e->IsArrayAccessor());
@@ -49,9 +48,9 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Minus) {
-  ParserImpl p{"- 1"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("- 1");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryOp());
 
@@ -67,17 +66,17 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Minus_InvalidRHS) {
-  ParserImpl p{"-if(a) {}"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("-if(a) {}");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:2: unable to parse right side of - expression");
+  EXPECT_EQ(p->error(), "1:2: unable to parse right side of - expression");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Bang) {
-  ParserImpl p{"!1"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("!1");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryOp());
 
@@ -93,17 +92,17 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Bang_InvalidRHS) {
-  ParserImpl p{"!if (a) {}"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("!if (a) {}");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:2: unable to parse right side of ! expression");
+  EXPECT_EQ(p->error(), "1:2: unable to parse right side of ! expression");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Any) {
-  ParserImpl p{"any(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("any(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -117,41 +116,41 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Any_MissingParenLeft) {
-  ParserImpl p{"any a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("any a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:5: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Any_MissingParenRight) {
-  ParserImpl p{"any(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("any(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:6: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Any_MissingIdentifier) {
-  ParserImpl p{"any()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("any()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:5: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Any_InvalidIdentifier) {
-  ParserImpl p{"any(123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("any(123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:5: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_All) {
-  ParserImpl p{"all(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("all(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -165,41 +164,41 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_All_MissingParenLeft) {
-  ParserImpl p{"all a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("all a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:5: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_All_MissingParenRight) {
-  ParserImpl p{"all(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("all(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:6: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_All_MissingIdentifier) {
-  ParserImpl p{"all()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("all()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:5: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_All_InvalidIdentifier) {
-  ParserImpl p{"all(123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("all(123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:5: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNan) {
-  ParserImpl p{"is_nan(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("is_nan(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -213,41 +212,41 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNan_MissingParenLeft) {
-  ParserImpl p{"is_nan a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_nan a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:8: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNan_MissingParenRight) {
-  ParserImpl p{"is_nan(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_nan(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:9: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNan_MissingIdentifier) {
-  ParserImpl p{"is_nan()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_nan()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:8: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNan_InvalidIdentifier) {
-  ParserImpl p{"is_nan(123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_nan(123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:8: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsInf) {
-  ParserImpl p{"is_inf(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("is_inf(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -261,41 +260,41 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsInf_MissingParenLeft) {
-  ParserImpl p{"is_inf a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_inf a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:8: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsInf_MissingParenRight) {
-  ParserImpl p{"is_inf(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_inf(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:9: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsInf_MissingIdentifier) {
-  ParserImpl p{"is_inf()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_inf()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:8: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsInf_InvalidIdentifier) {
-  ParserImpl p{"is_inf(123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_inf(123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:8: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsFinite) {
-  ParserImpl p{"is_finite(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("is_finite(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -309,41 +308,41 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsFinite_MissingParenLeft) {
-  ParserImpl p{"is_finite a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_finite a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:11: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsFinite_MissingParenRight) {
-  ParserImpl p{"is_finite(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_finite(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:12: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsFinite_MissingIdentifier) {
-  ParserImpl p{"is_finite()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_finite()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:11: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsFinite_InvalidIdentifier) {
-  ParserImpl p{"is_finite(123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_finite(123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:11: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNormal) {
-  ParserImpl p{"is_normal(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("is_normal(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -357,41 +356,41 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNormal_MissingParenLeft) {
-  ParserImpl p{"is_normal a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_normal a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:11: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNormal_MissingParenRight) {
-  ParserImpl p{"is_normal(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_normal(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:12: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:12: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNormal_MissingIdentifier) {
-  ParserImpl p{"is_normal()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_normal()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:11: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_IsNormal_InvalidIdentifier) {
-  ParserImpl p{"is_normal(123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("is_normal(123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:11: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot) {
-  ParserImpl p{"dot(a, b)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("dot(a, b)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -410,65 +409,65 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_MissingParenLeft) {
-  ParserImpl p{"dot a, b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot a, b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:5: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_MissingParenRight) {
-  ParserImpl p{"dot(a, b"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot(a, b");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:9: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_MissingFirstIdentifier) {
-  ParserImpl p{"dot(, a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot(, a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:5: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_MissingSecondIdentifier) {
-  ParserImpl p{"dot(a, )"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot(a, )");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:8: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_MissingComma) {
-  ParserImpl p{"dot(a b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot(a b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:7: missing , for method call");
+  EXPECT_EQ(p->error(), "1:7: missing , for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_InvalidFirstIdentifier) {
-  ParserImpl p{"dot(123, b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot(123, b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:5: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:5: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dot_InvalidSecondIdentifier) {
-  ParserImpl p{"dot(a, 123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dot(a, 123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:8: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct) {
-  ParserImpl p{"outer_product(a, b)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("outer_product(a, b)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryMethod());
 
@@ -487,65 +486,65 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_MissingParenLeft) {
-  ParserImpl p{"outer_product a, b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product a, b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing ( for method call");
+  EXPECT_EQ(p->error(), "1:15: missing ( for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_MissingParenRight) {
-  ParserImpl p{"outer_product(a, b"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product(a, b");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:19: missing ) for method call");
+  EXPECT_EQ(p->error(), "1:19: missing ) for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_MissingFirstIdentifier) {
-  ParserImpl p{"outer_product(, b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product(, b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:15: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_MissingSecondIdentifier) {
-  ParserImpl p{"outer_product(a, )"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product(a, )");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:18: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:18: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_MissingComma) {
-  ParserImpl p{"outer_product(a b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product(a b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:17: missing , for method call");
+  EXPECT_EQ(p->error(), "1:17: missing , for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_InvalidFirstIdentifier) {
-  ParserImpl p{"outer_product(123, b)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product(123, b)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:15: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_OuterProduct_InvalidSecondIdentifier) {
-  ParserImpl p{"outer_product(a, 123)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("outer_product(a, 123)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:18: missing identifier for method call");
+  EXPECT_EQ(p->error(), "1:18: missing identifier for method call");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_NoModifier) {
-  ParserImpl p{"dpdx(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("dpdx(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryDerivative());
 
@@ -561,9 +560,9 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_WithModifier) {
-  ParserImpl p{"dpdx<coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("dpdx<coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryDerivative());
 
@@ -579,73 +578,73 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_MissingLessThan) {
-  ParserImpl p{"dpdx coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:6: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_InvalidModifier) {
-  ParserImpl p{"dpdx<invalid>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx<invalid>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unable to parse derivative modifier");
+  EXPECT_EQ(p->error(), "1:6: unable to parse derivative modifier");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_EmptyModifer) {
-  ParserImpl p{"dpdx coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:6: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_MissingGreaterThan) {
-  ParserImpl p{"dpdx<coarse (a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx<coarse (a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing > for derivative modifier");
+  EXPECT_EQ(p->error(), "1:13: missing > for derivative modifier");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_MisisngLeftParen) {
-  ParserImpl p{"dpdx<coarse>a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx<coarse>a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:13: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_MissingRightParen) {
-  ParserImpl p{"dpdx<coarse>(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx<coarse>(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing ) for derivative method");
+  EXPECT_EQ(p->error(), "1:15: missing ) for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_MissingIdentifier) {
-  ParserImpl p{"dpdx<coarse>()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx<coarse>()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing identifier for derivative method");
+  EXPECT_EQ(p->error(), "1:14: missing identifier for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdx_InvalidIdentifeir) {
-  ParserImpl p{"dpdx<coarse>(12345)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdx<coarse>(12345)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing identifier for derivative method");
+  EXPECT_EQ(p->error(), "1:14: missing identifier for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_NoModifier) {
-  ParserImpl p{"dpdy(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("dpdy(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryDerivative());
 
@@ -661,9 +660,9 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_WithModifier) {
-  ParserImpl p{"dpdy<fine>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("dpdy<fine>(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryDerivative());
 
@@ -679,73 +678,73 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_MissingLessThan) {
-  ParserImpl p{"dpdy coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:6: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_InvalidModifier) {
-  ParserImpl p{"dpdy<invalid>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy<invalid>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: unable to parse derivative modifier");
+  EXPECT_EQ(p->error(), "1:6: unable to parse derivative modifier");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_EmptyModifer) {
-  ParserImpl p{"dpdy coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:6: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:6: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_MissingGreaterThan) {
-  ParserImpl p{"dpdy<coarse (a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy<coarse (a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing > for derivative modifier");
+  EXPECT_EQ(p->error(), "1:13: missing > for derivative modifier");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_MisisngLeftParen) {
-  ParserImpl p{"dpdy<coarse>a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy<coarse>a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:13: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:13: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_MissingRightParen) {
-  ParserImpl p{"dpdy<coarse>(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy<coarse>(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing ) for derivative method");
+  EXPECT_EQ(p->error(), "1:15: missing ) for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_MissingIdentifier) {
-  ParserImpl p{"dpdy<coarse>()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy<coarse>()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing identifier for derivative method");
+  EXPECT_EQ(p->error(), "1:14: missing identifier for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Dpdy_InvalidIdentifeir) {
-  ParserImpl p{"dpdy<coarse>(12345)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("dpdy<coarse>(12345)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:14: missing identifier for derivative method");
+  EXPECT_EQ(p->error(), "1:14: missing identifier for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_NoModifier) {
-  ParserImpl p{"fwidth(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("fwidth(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryDerivative());
 
@@ -761,9 +760,9 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_WithModifier) {
-  ParserImpl p{"fwidth<coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("fwidth<coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnaryDerivative());
 
@@ -779,67 +778,67 @@
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_MissingLessThan) {
-  ParserImpl p{"fwidth coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:8: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_InvalidModifier) {
-  ParserImpl p{"fwidth<invalid>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth<invalid>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse derivative modifier");
+  EXPECT_EQ(p->error(), "1:8: unable to parse derivative modifier");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_EmptyModifer) {
-  ParserImpl p{"fwidth coarse>(a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth coarse>(a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:8: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_MissingGreaterThan) {
-  ParserImpl p{"fwidth<coarse (a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth<coarse (a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing > for derivative modifier");
+  EXPECT_EQ(p->error(), "1:15: missing > for derivative modifier");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_MisisngLeftParen) {
-  ParserImpl p{"fwidth<coarse>a)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth<coarse>a)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing ( for derivative method");
+  EXPECT_EQ(p->error(), "1:15: missing ( for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_MissingRightParen) {
-  ParserImpl p{"fwidth<coarse>(a"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth<coarse>(a");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:17: missing ) for derivative method");
+  EXPECT_EQ(p->error(), "1:17: missing ) for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidth_MissingIdentifier) {
-  ParserImpl p{"fwidth<coarse>()"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth<coarse>()");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:16: missing identifier for derivative method");
+  EXPECT_EQ(p->error(), "1:16: missing identifier for derivative method");
 }
 
 TEST_F(ParserImplTest, UnaryExpression_Fwidht_InvalidIdentifeir) {
-  ParserImpl p{"fwidth<coarse>(12345)"};
-  auto e = p.unary_expression();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("fwidth<coarse>(12345)");
+  auto e = p->unary_expression();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:16: missing identifier for derivative method");
+  EXPECT_EQ(p->error(), "1:16: missing identifier for derivative method");
 }
 }  // namespace wgsl
 }  // namespace reader
diff --git a/src/reader/wgsl/parser_impl_unless_stmt_test.cc b/src/reader/wgsl/parser_impl_unless_stmt_test.cc
index f34d7d8..c9c419c 100644
--- a/src/reader/wgsl/parser_impl_unless_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_unless_stmt_test.cc
@@ -14,17 +14,16 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, UnlessStmt) {
-  ParserImpl p{"unless (a) { kill; }"};
-  auto e = p.unless_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("unless (a) { kill; }");
+  auto e = p->unless_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsUnless());
   ASSERT_NE(e->condition(), nullptr);
@@ -34,27 +33,27 @@
 }
 
 TEST_F(ParserImplTest, UnlessStmt_InvalidCondition) {
-  ParserImpl p{"unless(if(a){}) {}"};
-  auto e = p.unless_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("unless(if(a){}) {}");
+  auto e = p->unless_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, UnlessStmt_EmptyCondition) {
-  ParserImpl p{"unless() {}"};
-  auto e = p.unless_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("unless() {}");
+  auto e = p->unless_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:8: unable to parse expression");
+  EXPECT_EQ(p->error(), "1:8: unable to parse expression");
 }
 
 TEST_F(ParserImplTest, UnlessStmt_InvalidBody) {
-  ParserImpl p{"unless(a + 2 - 5 == true) { kill }"};
-  auto e = p.unless_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("unless(a + 2 - 5 == true) { kill }");
+  auto e = p->unless_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:34: missing ;");
+  EXPECT_EQ(p->error(), "1:34: missing ;");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_variable_decl_test.cc b/src/reader/wgsl/parser_impl_variable_decl_test.cc
index 73d7c17..a9220cb 100644
--- a/src/reader/wgsl/parser_impl_variable_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_variable_decl_test.cc
@@ -15,17 +15,16 @@
 #include "gtest/gtest.h"
 #include "src/ast/variable.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, VariableDecl_Parses) {
-  ParserImpl p{"var my_var : f32"};
-  auto var = p.variable_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("var my_var : f32");
+  auto var = p->variable_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(var, nullptr);
   ASSERT_EQ(var->name(), "my_var");
   ASSERT_NE(var->type(), nullptr);
@@ -35,27 +34,27 @@
 }
 
 TEST_F(ParserImplTest, VariableDecl_MissingVar) {
-  ParserImpl p{"my_var : f32"};
-  auto v = p.variable_decl();
+  auto p = parser("my_var : f32");
+  auto v = p->variable_decl();
   ASSERT_EQ(v, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
 
-  auto t = p.next();
+  auto t = p->next();
   ASSERT_TRUE(t.IsIdentifier());
 }
 
 TEST_F(ParserImplTest, VariableDecl_InvalidIdentDecl) {
-  ParserImpl p{"var my_var f32"};
-  auto v = p.variable_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var my_var f32");
+  auto v = p->variable_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(v, nullptr);
-  ASSERT_EQ(p.error(), "1:12: missing : for identifier declaration");
+  ASSERT_EQ(p->error(), "1:12: missing : for identifier declaration");
 }
 
 TEST_F(ParserImplTest, VariableDecl_WithStorageClass) {
-  ParserImpl p{"var<private> my_var : f32"};
-  auto v = p.variable_decl();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("var<private> my_var : f32");
+  auto v = p->variable_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(v, nullptr);
   EXPECT_EQ(v->name(), "my_var");
   EXPECT_TRUE(v->type()->IsF32());
@@ -63,11 +62,11 @@
 }
 
 TEST_F(ParserImplTest, VariableDecl_InvalidStorageClass) {
-  ParserImpl p{"var<unknown> my_var : f32"};
-  auto v = p.variable_decl();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var<unknown> my_var : f32");
+  auto v = p->variable_decl();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(v, nullptr);
-  EXPECT_EQ(p.error(), "1:5: invalid storage class for variable decoration");
+  EXPECT_EQ(p->error(), "1:5: invalid storage class for variable decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_variable_decoration_list_test.cc b/src/reader/wgsl/parser_impl_variable_decoration_list_test.cc
index 19029e0..6adbd5d 100644
--- a/src/reader/wgsl/parser_impl_variable_decoration_list_test.cc
+++ b/src/reader/wgsl/parser_impl_variable_decoration_list_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/builtin_decoration.h"
 #include "src/ast/location_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, VariableDecorationList_Parses) {
-  ParserImpl p{R"([[location 4, builtin position]])"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser(R"([[location 4, builtin position]])");
+  auto decos = p->variable_decoration_list();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(decos.size(), 2);
   ASSERT_TRUE(decos[0]->IsLocation());
   EXPECT_EQ(decos[0]->AsLocation()->value(), 4);
@@ -35,45 +34,45 @@
 }
 
 TEST_F(ParserImplTest, VariableDecorationList_Empty) {
-  ParserImpl p{R"([[]])"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:3: empty variable decoration list");
+  auto p = parser(R"([[]])");
+  auto decos = p->variable_decoration_list();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:3: empty variable decoration list");
 }
 
 TEST_F(ParserImplTest, VariableDecorationList_Invalid) {
-  ParserImpl p{R"([[invalid]])"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:3: missing variable decoration for decoration list");
+  auto p = parser(R"([[invalid]])");
+  auto decos = p->variable_decoration_list();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:3: missing variable decoration for decoration list");
 }
 
 TEST_F(ParserImplTest, VariableDecorationList_ExtraComma) {
-  ParserImpl p{R"([[builtin position, ]])"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:21: missing variable decoration after comma");
+  auto p = parser(R"([[builtin position, ]])");
+  auto decos = p->variable_decoration_list();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:21: missing variable decoration after comma");
 }
 
 TEST_F(ParserImplTest, VariableDecorationList_MissingComma) {
-  ParserImpl p{R"([[binding 4 location 5]])"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:13: missing comma in variable decoration list");
+  auto p = parser(R"([[binding 4 location 5]])");
+  auto decos = p->variable_decoration_list();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:13: missing comma in variable decoration list");
 }
 
 TEST_F(ParserImplTest, VariableDecorationList_BadDecoration) {
-  ParserImpl p{R"([[location bad]])"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:12: invalid value for location decoration");
+  auto p = parser(R"([[location bad]])");
+  auto decos = p->variable_decoration_list();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:12: invalid value for location decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecorationList_InvalidBuiltin) {
-  ParserImpl p{"[[builtin invalid]]"};
-  auto decos = p.variable_decoration_list();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:11: invalid value for builtin decoration");
+  auto p = parser("[[builtin invalid]]");
+  auto decos = p->variable_decoration_list();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:11: invalid value for builtin decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_variable_decoration_test.cc b/src/reader/wgsl/parser_impl_variable_decoration_test.cc
index 311dd5a..5001f4a 100644
--- a/src/reader/wgsl/parser_impl_variable_decoration_test.cc
+++ b/src/reader/wgsl/parser_impl_variable_decoration_test.cc
@@ -18,18 +18,17 @@
 #include "src/ast/location_decoration.h"
 #include "src/ast/set_decoration.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, VariableDecoration_Location) {
-  ParserImpl p{"location 4"};
-  auto deco = p.variable_decoration();
+  auto p = parser("location 4");
+  auto deco = p->variable_decoration();
   ASSERT_NE(deco, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(deco->IsLocation());
 
   auto loc = deco->AsLocation();
@@ -37,25 +36,25 @@
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Location_MissingValue) {
-  ParserImpl p{"location"};
-  auto deco = p.variable_decoration();
+  auto p = parser("location");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:9: invalid value for location decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:9: invalid value for location decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Location_MissingInvalid) {
-  ParserImpl p{"location nan"};
-  auto deco = p.variable_decoration();
+  auto p = parser("location nan");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:10: invalid value for location decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:10: invalid value for location decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Builtin) {
-  ParserImpl p{"builtin frag_depth"};
-  auto deco = p.variable_decoration();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("builtin frag_depth");
+  auto deco = p->variable_decoration();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(deco, nullptr);
   ASSERT_TRUE(deco->IsBuiltin());
 
@@ -64,26 +63,26 @@
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Builtin_MissingValue) {
-  ParserImpl p{"builtin"};
-  auto deco = p.variable_decoration();
+  auto p = parser("builtin");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: invalid value for builtin decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: invalid value for builtin decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Builtin_MissingInvalid) {
-  ParserImpl p{"builtin 3"};
-  auto deco = p.variable_decoration();
+  auto p = parser("builtin 3");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:9: invalid value for builtin decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:9: invalid value for builtin decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Binding) {
-  ParserImpl p{"binding 4"};
-  auto deco = p.variable_decoration();
+  auto p = parser("binding 4");
+  auto deco = p->variable_decoration();
   ASSERT_NE(deco, nullptr);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
   ASSERT_TRUE(deco->IsBinding());
 
   auto binding = deco->AsBinding();
@@ -91,25 +90,25 @@
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Binding_MissingValue) {
-  ParserImpl p{"binding"};
-  auto deco = p.variable_decoration();
+  auto p = parser("binding");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:8: invalid value for binding decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:8: invalid value for binding decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Binding_MissingInvalid) {
-  ParserImpl p{"binding nan"};
-  auto deco = p.variable_decoration();
+  auto p = parser("binding nan");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:9: invalid value for binding decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:9: invalid value for binding decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_set) {
-  ParserImpl p{"set 4"};
-  auto deco = p.variable_decoration();
-  ASSERT_FALSE(p.has_error());
+  auto p = parser("set 4");
+  auto deco = p->variable_decoration();
+  ASSERT_FALSE(p->has_error());
   ASSERT_NE(deco.get(), nullptr);
   ASSERT_TRUE(deco->IsSet());
 
@@ -118,19 +117,19 @@
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Set_MissingValue) {
-  ParserImpl p{"set"};
-  auto deco = p.variable_decoration();
+  auto p = parser("set");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:4: invalid value for set decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:4: invalid value for set decoration");
 }
 
 TEST_F(ParserImplTest, VariableDecoration_Set_MissingInvalid) {
-  ParserImpl p{"set nan"};
-  auto deco = p.variable_decoration();
+  auto p = parser("set nan");
+  auto deco = p->variable_decoration();
   ASSERT_EQ(deco, nullptr);
-  ASSERT_TRUE(p.has_error());
-  EXPECT_EQ(p.error(), "1:5: invalid value for set decoration");
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(p->error(), "1:5: invalid value for set decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_variable_ident_decl_test.cc b/src/reader/wgsl/parser_impl_variable_ident_decl_test.cc
index 393884b..458390f 100644
--- a/src/reader/wgsl/parser_impl_variable_ident_decl_test.cc
+++ b/src/reader/wgsl/parser_impl_variable_ident_decl_test.cc
@@ -14,69 +14,68 @@
 
 #include "gtest/gtest.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, VariableIdentDecl_Parses) {
-  ParserImpl p{"my_var : f32"};
+  auto p = parser("my_var : f32");
   std::string name;
   ast::type::Type* type;
-  std::tie(name, type) = p.variable_ident_decl();
-  ASSERT_FALSE(p.has_error());
+  std::tie(name, type) = p->variable_ident_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(name, "my_var");
   ASSERT_NE(type, nullptr);
   ASSERT_TRUE(type->IsF32());
 }
 
 TEST_F(ParserImplTest, VariableIdentDecl_MissingIdent) {
-  ParserImpl p{": f32"};
+  auto p = parser(": f32");
   std::string name;
   ast::type::Type* type;
-  std::tie(name, type) = p.variable_ident_decl();
-  ASSERT_FALSE(p.has_error());
+  std::tie(name, type) = p->variable_ident_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(name, "");
   ASSERT_EQ(type, nullptr);
 
-  auto t = p.next();
+  auto t = p->next();
   ASSERT_TRUE(t.IsColon());
 }
 
 TEST_F(ParserImplTest, VariableIdentDecl_MissingColon) {
-  ParserImpl p{"my_var f32"};
-  auto r = p.variable_ident_decl();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:8: missing : for identifier declaration");
+  auto p = parser("my_var f32");
+  auto r = p->variable_ident_decl();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:8: missing : for identifier declaration");
 }
 
 TEST_F(ParserImplTest, VariableIdentDecl_MissingType) {
-  ParserImpl p{"my_var :"};
-  auto r = p.variable_ident_decl();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:9: invalid type for identifier declaration");
+  auto p = parser("my_var :");
+  auto r = p->variable_ident_decl();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:9: invalid type for identifier declaration");
 }
 
 TEST_F(ParserImplTest, VariableIdentDecl_InvalidIdent) {
-  ParserImpl p{"123 : f32"};
+  auto p = parser("123 : f32");
   std::string name;
   ast::type::Type* type;
-  std::tie(name, type) = p.variable_ident_decl();
-  ASSERT_FALSE(p.has_error());
+  std::tie(name, type) = p->variable_ident_decl();
+  ASSERT_FALSE(p->has_error());
   ASSERT_EQ(name, "");
   ASSERT_EQ(type, nullptr);
 
-  auto t = p.next();
+  auto t = p->next();
   ASSERT_TRUE(t.IsIntLiteral());
 }
 
 TEST_F(ParserImplTest, VariableIdentDecl_InvalidType) {
-  ParserImpl p{"my_var : invalid"};
-  auto r = p.variable_ident_decl();
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:10: unknown type alias 'invalid'");
+  auto p = parser("my_var : invalid");
+  auto r = p->variable_ident_decl();
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:10: unknown type alias 'invalid'");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_variable_stmt_test.cc b/src/reader/wgsl/parser_impl_variable_stmt_test.cc
index bbbfdc6..c090053 100644
--- a/src/reader/wgsl/parser_impl_variable_stmt_test.cc
+++ b/src/reader/wgsl/parser_impl_variable_stmt_test.cc
@@ -16,17 +16,16 @@
 #include "src/ast/statement.h"
 #include "src/ast/variable_statement.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
 
-using ParserImplTest = testing::Test;
-
 TEST_F(ParserImplTest, VariableStmt_VariableDecl) {
-  ParserImpl p{"var a : i32;"};
-  auto e = p.variable_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("var a : i32;");
+  auto e = p->variable_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsVariable());
   ASSERT_NE(e->variable(), nullptr);
@@ -36,9 +35,9 @@
 }
 
 TEST_F(ParserImplTest, VariableStmt_VariableDecl_WithInit) {
-  ParserImpl p{"var a : i32 = 1;"};
-  auto e = p.variable_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("var a : i32 = 1;");
+  auto e = p->variable_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsVariable());
   ASSERT_NE(e->variable(), nullptr);
@@ -49,59 +48,59 @@
 }
 
 TEST_F(ParserImplTest, VariableStmt_VariableDecl_Invalid) {
-  ParserImpl p{"var a : invalid;"};
-  auto e = p.variable_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var a : invalid;");
+  auto e = p->variable_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:9: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:9: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, VariableStmt_VariableDecl_InitializerInvalid) {
-  ParserImpl p{"var a : i32 = if(a) {}"};
-  auto e = p.variable_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("var a : i32 = if(a) {}");
+  auto e = p->variable_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing initializer for variable declaration");
+  EXPECT_EQ(p->error(), "1:15: missing initializer for variable declaration");
 }
 
 TEST_F(ParserImplTest, VariableStmt_Const) {
-  ParserImpl p{"const a : i32 = 1"};
-  auto e = p.variable_stmt();
-  ASSERT_FALSE(p.has_error()) << p.error();
+  auto p = parser("const a : i32 = 1");
+  auto e = p->variable_stmt();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(e, nullptr);
   ASSERT_TRUE(e->IsVariable());
 }
 
 TEST_F(ParserImplTest, VariableStmt_Const_InvalidVarIdent) {
-  ParserImpl p{"const a : invalid = 1"};
-  auto e = p.variable_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a : invalid = 1");
+  auto e = p->variable_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:11: unknown type alias 'invalid'");
+  EXPECT_EQ(p->error(), "1:11: unknown type alias 'invalid'");
 }
 
 TEST_F(ParserImplTest, VariableStmt_Const_MissingEqual) {
-  ParserImpl p{"const a : i32 1"};
-  auto e = p.variable_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a : i32 1");
+  auto e = p->variable_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:15: missing = for constant declaration");
+  EXPECT_EQ(p->error(), "1:15: missing = for constant declaration");
 }
 
 TEST_F(ParserImplTest, VariableStmt_Const_MissingInitializer) {
-  ParserImpl p{"const a : i32 ="};
-  auto e = p.variable_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a : i32 =");
+  auto e = p->variable_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:16: missing initializer for const declaration");
+  EXPECT_EQ(p->error(), "1:16: missing initializer for const declaration");
 }
 
 TEST_F(ParserImplTest, VariableStmt_Const_InvalidInitializer) {
-  ParserImpl p{"const a : i32 = if (a) {}"};
-  auto e = p.variable_stmt();
-  ASSERT_TRUE(p.has_error());
+  auto p = parser("const a : i32 = if (a) {}");
+  auto e = p->variable_stmt();
+  ASSERT_TRUE(p->has_error());
   ASSERT_EQ(e, nullptr);
-  EXPECT_EQ(p.error(), "1:17: missing initializer for const declaration");
+  EXPECT_EQ(p->error(), "1:17: missing initializer for const declaration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_impl_variable_storage_decoration_test.cc b/src/reader/wgsl/parser_impl_variable_storage_decoration_test.cc
index 04963d7..845118c 100644
--- a/src/reader/wgsl/parser_impl_variable_storage_decoration_test.cc
+++ b/src/reader/wgsl/parser_impl_variable_storage_decoration_test.cc
@@ -15,12 +15,12 @@
 #include "gtest/gtest.h"
 #include "src/ast/storage_class.h"
 #include "src/reader/wgsl/parser_impl.h"
+#include "src/reader/wgsl/parser_impl_test_helper.h"
 
 namespace tint {
 namespace reader {
 namespace wgsl {
-
-using ParserImplTest = testing::Test;
+namespace {
 
 struct VariableStorageData {
   const char* input;
@@ -30,16 +30,41 @@
   out << std::string(data.input);
   return out;
 }
-using VariableStorageTest = testing::TestWithParam<VariableStorageData>;
+
+class VariableStorageTest : public testing::TestWithParam<VariableStorageData> {
+ public:
+  VariableStorageTest() = default;
+  ~VariableStorageTest() = default;
+
+  void SetUp() { ctx_.type_mgr = &tm_; }
+
+  void TearDown() {
+    impl_ = nullptr;
+    ctx_.type_mgr = nullptr;
+  }
+
+  ParserImpl* parser(const std::string& str) {
+    impl_ = std::make_unique<ParserImpl>(ctx_, str);
+    return impl_.get();
+  }
+
+ private:
+  std::unique_ptr<ParserImpl> impl_;
+  Context ctx_;
+  TypeManager tm_;
+};
+
+}  // namespace
+
 TEST_P(VariableStorageTest, Parses) {
   auto params = GetParam();
-  ParserImpl p{std::string("<") + params.input + ">"};
+  auto p = parser(std::string("<") + params.input + ">");
 
-  auto sc = p.variable_storage_decoration();
-  ASSERT_FALSE(p.has_error());
+  auto sc = p->variable_storage_decoration();
+  ASSERT_FALSE(p->has_error());
   EXPECT_EQ(sc, params.result);
 
-  auto t = p.next();
+  auto t = p->next();
   EXPECT_TRUE(t.IsEof());
 }
 INSTANTIATE_TEST_SUITE_P(
@@ -60,37 +85,37 @@
         VariableStorageData{"function", ast::StorageClass::kFunction}));
 
 TEST_F(ParserImplTest, VariableStorageDecoration_NoMatch) {
-  ParserImpl p{"<not-a-storage-class>"};
-  auto sc = p.variable_storage_decoration();
+  auto p = parser("<not-a-storage-class>");
+  auto sc = p->variable_storage_decoration();
   ASSERT_EQ(sc, ast::StorageClass::kNone);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:2: invalid storage class for variable decoration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:2: invalid storage class for variable decoration");
 }
 
 TEST_F(ParserImplTest, VariableStorageDecoration_Empty) {
-  ParserImpl p{"<>"};
-  auto sc = p.variable_storage_decoration();
+  auto p = parser("<>");
+  auto sc = p->variable_storage_decoration();
   ASSERT_EQ(sc, ast::StorageClass::kNone);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:2: invalid storage class for variable decoration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:2: invalid storage class for variable decoration");
 }
 
 TEST_F(ParserImplTest, VariableStorageDecoration_MissingLessThan) {
-  ParserImpl p{"in>"};
-  auto sc = p.variable_storage_decoration();
+  auto p = parser("in>");
+  auto sc = p->variable_storage_decoration();
   ASSERT_EQ(sc, ast::StorageClass::kNone);
-  ASSERT_FALSE(p.has_error());
+  ASSERT_FALSE(p->has_error());
 
-  auto t = p.next();
+  auto t = p->next();
   ASSERT_TRUE(t.IsIn());
 }
 
 TEST_F(ParserImplTest, VariableStorageDecoration_MissingGreaterThan) {
-  ParserImpl p{"<in"};
-  auto sc = p.variable_storage_decoration();
+  auto p = parser("<in");
+  auto sc = p->variable_storage_decoration();
   ASSERT_EQ(sc, ast::StorageClass::kNone);
-  ASSERT_TRUE(p.has_error());
-  ASSERT_EQ(p.error(), "1:4: missing > for variable decoration");
+  ASSERT_TRUE(p->has_error());
+  ASSERT_EQ(p->error(), "1:4: missing > for variable decoration");
 }
 
 }  // namespace wgsl
diff --git a/src/reader/wgsl/parser_test.cc b/src/reader/wgsl/parser_test.cc
index 6ef3016..4788e09 100644
--- a/src/reader/wgsl/parser_test.cc
+++ b/src/reader/wgsl/parser_test.cc
@@ -15,6 +15,7 @@
 #include "src/reader/wgsl/parser.h"
 
 #include "gtest/gtest.h"
+#include "src/context.h"
 
 namespace tint {
 namespace reader {
@@ -23,12 +24,19 @@
 using ParserTest = testing::Test;
 
 TEST_F(ParserTest, Empty) {
-  Parser p{""};
+  TypeManager tm;
+  Context ctx;
+  ctx.type_mgr = &tm;
+  Parser p(ctx, "");
   ASSERT_TRUE(p.Parse()) << p.error();
 }
 
 TEST_F(ParserTest, DISABLED_Parses) {
-  Parser p{R"(
+  TypeManager tm;
+  Context ctx;
+  ctx.type_mgr = &tm;
+
+  Parser p(ctx, R"(
 import "GLSL.std.430" as glsl;
 
 [[location 0]] var<out> gl_FragColor : vec4<f32>;
@@ -36,7 +44,7 @@
 fn main() -> void {
   gl_FragColor = vec4<f32>(.4, .2, .3, 1);
 }
-)"};
+)");
   ASSERT_TRUE(p.Parse()) << p.error();
 
   auto m = p.module();
@@ -46,12 +54,13 @@
 }
 
 TEST_F(ParserTest, DISABLED_HandlesError) {
-  Parser p{R"(
+  Context ctx;
+  Parser p(ctx, R"(
 import "GLSL.std.430" as glsl;
 
 fn main() ->  {  # missing return type
   return;
-})"};
+})");
 
   ASSERT_FALSE(p.Parse());
   ASSERT_TRUE(p.has_error());
diff --git a/src/type_manager.cc b/src/type_manager.cc
index 5380f5f..e52c3ff 100644
--- a/src/type_manager.cc
+++ b/src/type_manager.cc
@@ -17,25 +17,6 @@
 #include <utility>
 
 namespace tint {
-namespace {
-
-TypeManager* manager_ = nullptr;
-
-}  // namespace
-
-// static
-TypeManager* TypeManager::Instance() {
-  if (!manager_) {
-    manager_ = new TypeManager();
-  }
-  return manager_;
-}
-
-// static
-void TypeManager::Destroy() {
-  delete manager_;
-  manager_ = nullptr;
-}
 
 TypeManager::TypeManager() = default;
 
diff --git a/src/type_manager.h b/src/type_manager.h
index a518b22..61ca864 100644
--- a/src/type_manager.h
+++ b/src/type_manager.h
@@ -24,16 +24,10 @@
 namespace tint {
 
 /// The type manager holds all the pointers to the known types.
-///
-/// Note, the type manager is a singleton. Any synchronization for the manager
-/// must be done by the caller.
 class TypeManager {
  public:
-  /// @returns a pointer to the type manager
-  static TypeManager* Instance();
-  /// Frees the type manager and any associated types. The types should not be
-  /// used after the manager is freed.
-  static void Destroy();
+  TypeManager();
+  ~TypeManager();
 
   /// Get the given type from the type manager
   /// @param type The type to register
@@ -41,9 +35,6 @@
   ast::type::Type* Get(std::unique_ptr<ast::type::Type> type);
 
  private:
-  TypeManager();
-  ~TypeManager();
-
   std::unordered_map<std::string, std::unique_ptr<ast::type::Type>> types_;
 };
 
diff --git a/src/type_manager_test.cc b/src/type_manager_test.cc
index 821e559..5a90dd1 100644
--- a/src/type_manager_test.cc
+++ b/src/type_manager_test.cc
@@ -22,60 +22,33 @@
 
 using TypeManagerTest = testing::Test;
 
-TEST_F(TypeManagerTest, Singleton) {
-  auto tm = TypeManager::Instance();
-  ASSERT_NE(tm, nullptr);
-  ASSERT_EQ(tm, TypeManager::Instance());
-
-  TypeManager::Destroy();
-}
-
-TEST_F(TypeManagerTest, Destroy) {
-  auto tm = TypeManager::Instance();
-  ASSERT_NE(tm, nullptr);
-  ASSERT_EQ(tm, TypeManager::Instance());
-
-  TypeManager::Destroy();
-
-  tm = TypeManager::Instance();
-  ASSERT_NE(tm, nullptr);
-
-  TypeManager::Destroy();
-}
-
 TEST_F(TypeManagerTest, GetUnregistered) {
-  auto tm = TypeManager::Instance();
-  auto t = tm->Get(std::make_unique<ast::type::I32Type>());
+  TypeManager tm;
+  auto t = tm.Get(std::make_unique<ast::type::I32Type>());
   ASSERT_NE(t, nullptr);
   EXPECT_TRUE(t->IsI32());
-
-  TypeManager::Destroy();
 }
 
 TEST_F(TypeManagerTest, GetSameTypeReturnsSamePtr) {
-  auto tm = TypeManager::Instance();
-  auto t = tm->Get(std::make_unique<ast::type::I32Type>());
+  TypeManager tm;
+  auto t = tm.Get(std::make_unique<ast::type::I32Type>());
   ASSERT_NE(t, nullptr);
   EXPECT_TRUE(t->IsI32());
 
-  auto t2 = tm->Get(std::make_unique<ast::type::I32Type>());
+  auto t2 = tm.Get(std::make_unique<ast::type::I32Type>());
   EXPECT_EQ(t, t2);
-
-  TypeManager::Destroy();
 }
 
 TEST_F(TypeManagerTest, GetDifferentTypeReturnsDifferentPtr) {
-  auto tm = TypeManager::Instance();
-  auto t = tm->Get(std::make_unique<ast::type::I32Type>());
+  TypeManager tm;
+  auto t = tm.Get(std::make_unique<ast::type::I32Type>());
   ASSERT_NE(t, nullptr);
   EXPECT_TRUE(t->IsI32());
 
-  auto t2 = tm->Get(std::make_unique<ast::type::U32Type>());
+  auto t2 = tm.Get(std::make_unique<ast::type::U32Type>());
   ASSERT_NE(t2, nullptr);
   EXPECT_NE(t, t2);
   EXPECT_TRUE(t2->IsU32());
-
-  TypeManager::Destroy();
 }
 
 }  // namespace tint