Split WGSL generator tests to individual files.

This makes it easier to find and track tests as the generator grows.

Bug: tint:4
Change-Id: I9660e459f3ffd33f3048a331f23623318af013e0
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/16840
Reviewed-by: David Neto <dneto@google.com>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0cc9488..d51da20 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -404,6 +404,14 @@
 if(${TINT_BUILD_WGSL_WRITER})
   list(APPEND TINT_TEST_SRCS
     writer/wgsl/generator_impl_test.cc
+    writer/wgsl/generator_impl_alias_type_test.cc
+    writer/wgsl/generator_impl_array_accessor_test.cc
+    writer/wgsl/generator_impl_entry_point_test.cc
+    writer/wgsl/generator_impl_identifier_test.cc
+    writer/wgsl/generator_impl_import_test.cc
+    writer/wgsl/generator_impl_initializer_test.cc
+    writer/wgsl/generator_impl_type_test.cc
+    writer/wgsl/generator_impl_variable_test.cc
   )
 endif()
 add_executable(tint_unittests ${TINT_TEST_SRCS})
diff --git a/src/writer/wgsl/generator_impl.cc b/src/writer/wgsl/generator_impl.cc
index 46c6e65..833b821 100644
--- a/src/writer/wgsl/generator_impl.cc
+++ b/src/writer/wgsl/generator_impl.cc
@@ -15,6 +15,7 @@
 #include "src/writer/wgsl/generator_impl.h"
 
 #include <cassert>
+#include <limits>
 
 #include "src/ast/array_accessor_expression.h"
 #include "src/ast/binding_decoration.h"
diff --git a/src/writer/wgsl/generator_impl_alias_type_test.cc b/src/writer/wgsl/generator_impl_alias_type_test.cc
new file mode 100644
index 0000000..ef4d6f3
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_alias_type_test.cc
@@ -0,0 +1,73 @@
+// 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.
+
+#include "gtest/gtest.h"
+#include "src/ast/struct.h"
+#include "src/ast/struct_member.h"
+#include "src/ast/struct_member_decoration.h"
+#include "src/ast/struct_member_offset_decoration.h"
+#include "src/ast/type/f32_type.h"
+#include "src/ast/type/i32_type.h"
+#include "src/ast/type/struct_type.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitAliasType_F32) {
+  ast::type::F32Type f32;
+  ast::type::AliasType alias("a", &f32);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitAliasType(&alias)) << g.error();
+  EXPECT_EQ(g.result(), R"(type a = f32;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitAliasType_Struct) {
+  ast::type::I32Type i32;
+  ast::type::F32Type f32;
+
+  std::vector<std::unique_ptr<ast::StructMember>> members;
+  members.push_back(std::make_unique<ast::StructMember>(
+      "a", &f32, std::vector<std::unique_ptr<ast::StructMemberDecoration>>{}));
+
+  std::vector<std::unique_ptr<ast::StructMemberDecoration>> b_deco;
+  b_deco.push_back(std::make_unique<ast::StructMemberOffsetDecoration>(4));
+  members.push_back(
+      std::make_unique<ast::StructMember>("b", &i32, std::move(b_deco)));
+
+  auto str = std::make_unique<ast::Struct>();
+  str->set_members(std::move(members));
+
+  ast::type::StructType s(std::move(str));
+  ast::type::AliasType alias("a", &s);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitAliasType(&alias)) << g.error();
+  EXPECT_EQ(g.result(), R"(type a = struct {
+  a : f32;
+  [[offset 4]] b : i32;
+};
+)");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_array_accessor_test.cc b/src/writer/wgsl/generator_impl_array_accessor_test.cc
new file mode 100644
index 0000000..51f7c6c
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_array_accessor_test.cc
@@ -0,0 +1,57 @@
+// 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.
+
+#include <memory>
+
+#include "gtest/gtest.h"
+#include "src/ast/array_accessor_expression.h"
+#include "src/ast/const_initializer_expression.h"
+#include "src/ast/identifier_expression.h"
+#include "src/ast/int_literal.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitExpression_ArrayAccessor) {
+  auto lit = std::make_unique<ast::IntLiteral>(5);
+  auto idx = std::make_unique<ast::ConstInitializerExpression>(std::move(lit));
+  auto ary = std::make_unique<ast::IdentifierExpression>("ary");
+
+  ast::ArrayAccessorExpression expr(std::move(ary), std::move(idx));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitExpression(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "ary[5]");
+}
+
+TEST_F(GeneratorImplTest, EmitArrayAccessor) {
+  auto ary = std::make_unique<ast::IdentifierExpression>("ary");
+  auto idx = std::make_unique<ast::IdentifierExpression>("idx");
+
+  ast::ArrayAccessorExpression expr(std::move(ary), std::move(idx));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitArrayAccessor(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "ary[idx]");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_entry_point_test.cc b/src/writer/wgsl/generator_impl_entry_point_test.cc
new file mode 100644
index 0000000..372934f
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_entry_point_test.cc
@@ -0,0 +1,46 @@
+// 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.
+
+#include "gtest/gtest.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitEntryPoint_NoName) {
+  ast::EntryPoint ep(ast::PipelineStage::kFragment, "", "frag_main");
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitEntryPoint(&ep)) << g.error();
+  EXPECT_EQ(g.result(), R"(entry_point fragment = frag_main;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitEntryPoint_WithName) {
+  ast::EntryPoint ep(ast::PipelineStage::kFragment, "main", "frag_main");
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitEntryPoint(&ep)) << g.error();
+  EXPECT_EQ(g.result(), R"(entry_point fragment as "main" = frag_main;
+)");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_identifier_test.cc b/src/writer/wgsl/generator_impl_identifier_test.cc
new file mode 100644
index 0000000..14e87e3
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_identifier_test.cc
@@ -0,0 +1,52 @@
+// 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.
+
+#include "gtest/gtest.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitExpression_Identifier) {
+  ast::IdentifierExpression i(std::vector<std::string>{"std", "glsl"});
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitExpression(&i)) << g.error();
+  EXPECT_EQ(g.result(), "std::glsl");
+}
+
+TEST_F(GeneratorImplTest, EmitIdentifierExpression_Single) {
+  ast::IdentifierExpression i("glsl");
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitExpression(&i)) << g.error();
+  EXPECT_EQ(g.result(), "glsl");
+}
+
+TEST_F(GeneratorImplTest, EmitIdentifierExpression_MultipleNames) {
+  ast::IdentifierExpression i({"std", "glsl", "init"});
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitExpression(&i)) << g.error();
+  EXPECT_EQ(g.result(), "std::glsl::init");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_import_test.cc b/src/writer/wgsl/generator_impl_import_test.cc
new file mode 100644
index 0000000..9972eb7
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_import_test.cc
@@ -0,0 +1,37 @@
+// 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.
+
+#include "gtest/gtest.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitImport) {
+  ast::Import import("GLSL.std.450", "std::glsl");
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitImport(&import)) << g.error();
+  EXPECT_EQ(g.result(), R"(import "GLSL.std.450" as std::glsl;
+)");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_initializer_test.cc b/src/writer/wgsl/generator_impl_initializer_test.cc
new file mode 100644
index 0000000..6a6876f
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_initializer_test.cc
@@ -0,0 +1,227 @@
+// 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.
+
+#include <memory>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "src/ast/bool_literal.h"
+#include "src/ast/const_initializer_expression.h"
+#include "src/ast/float_literal.h"
+#include "src/ast/int_literal.h"
+#include "src/ast/type/array_type.h"
+#include "src/ast/type/bool_type.h"
+#include "src/ast/type/f32_type.h"
+#include "src/ast/type/i32_type.h"
+#include "src/ast/type/matrix_type.h"
+#include "src/ast/type/u32_type.h"
+#include "src/ast/type/vector_type.h"
+#include "src/ast/uint_literal.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitInitializer_Bool) {
+  auto lit = std::make_unique<ast::BoolLiteral>(false);
+  ast::ConstInitializerExpression expr(std::move(lit));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "false");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Int) {
+  auto lit = std::make_unique<ast::IntLiteral>(-12345);
+  ast::ConstInitializerExpression expr(std::move(lit));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "-12345");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_UInt) {
+  auto lit = std::make_unique<ast::UintLiteral>(56779);
+  ast::ConstInitializerExpression expr(std::move(lit));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "56779u");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Float) {
+  auto lit = std::make_unique<ast::FloatLiteral>(1.5e27);
+  ast::ConstInitializerExpression expr(std::move(lit));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "1.49999995e+27");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Float) {
+  ast::type::F32Type f32;
+
+  auto lit = std::make_unique<ast::FloatLiteral>(-1.2e-5);
+  std::vector<std::unique_ptr<ast::Expression>> values;
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
+
+  ast::TypeInitializerExpression expr(&f32, std::move(values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "f32(-1.20000004e-05)");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Bool) {
+  ast::type::BoolType b;
+
+  auto lit = std::make_unique<ast::BoolLiteral>(true);
+  std::vector<std::unique_ptr<ast::Expression>> values;
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
+
+  ast::TypeInitializerExpression expr(&b, std::move(values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "bool(true)");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Int) {
+  ast::type::I32Type i32;
+
+  auto lit = std::make_unique<ast::IntLiteral>(-12345);
+  std::vector<std::unique_ptr<ast::Expression>> values;
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
+
+  ast::TypeInitializerExpression expr(&i32, std::move(values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "i32(-12345)");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Uint) {
+  ast::type::U32Type u32;
+
+  auto lit = std::make_unique<ast::UintLiteral>(12345);
+  std::vector<std::unique_ptr<ast::Expression>> values;
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
+
+  ast::TypeInitializerExpression expr(&u32, std::move(values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "u32(12345u)");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Vec) {
+  ast::type::F32Type f32;
+  ast::type::VectorType vec(&f32, 3);
+
+  auto lit1 = std::make_unique<ast::FloatLiteral>(1.f);
+  auto lit2 = std::make_unique<ast::FloatLiteral>(2.f);
+  auto lit3 = std::make_unique<ast::FloatLiteral>(3.f);
+  std::vector<std::unique_ptr<ast::Expression>> values;
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit1)));
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit2)));
+  values.push_back(
+      std::make_unique<ast::ConstInitializerExpression>(std::move(lit3)));
+
+  ast::TypeInitializerExpression expr(&vec, std::move(values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), "vec3<f32>(1.00000000, 2.00000000, 3.00000000)");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Mat) {
+  ast::type::F32Type f32;
+  ast::type::MatrixType mat(&f32, 3, 2);
+
+  ast::type::VectorType vec(&f32, 2);
+
+  std::vector<std::unique_ptr<ast::Expression>> mat_values;
+
+  for (size_t i = 0; i < 3; i++) {
+    auto lit1 = std::make_unique<ast::FloatLiteral>(1.f + (i * 2));
+    auto lit2 = std::make_unique<ast::FloatLiteral>(2.f + (i * 2));
+
+    std::vector<std::unique_ptr<ast::Expression>> values;
+    values.push_back(
+        std::make_unique<ast::ConstInitializerExpression>(std::move(lit1)));
+    values.push_back(
+        std::make_unique<ast::ConstInitializerExpression>(std::move(lit2)));
+
+    mat_values.push_back(std::make_unique<ast::TypeInitializerExpression>(
+        &vec, std::move(values)));
+  }
+
+  ast::TypeInitializerExpression expr(&mat, std::move(mat_values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(),
+            std::string("mat2x3<f32>(vec2<f32>(1.00000000, 2.00000000), ") +
+                "vec2<f32>(3.00000000, 4.00000000), " +
+                "vec2<f32>(5.00000000, 6.00000000))");
+}
+
+TEST_F(GeneratorImplTest, EmitInitializer_Type_Array) {
+  ast::type::F32Type f32;
+  ast::type::VectorType vec(&f32, 3);
+  ast::type::ArrayType ary(&vec, 3);
+
+  std::vector<std::unique_ptr<ast::Expression>> ary_values;
+
+  for (size_t i = 0; i < 3; i++) {
+    auto lit1 = std::make_unique<ast::FloatLiteral>(1.f + (i * 3));
+    auto lit2 = std::make_unique<ast::FloatLiteral>(2.f + (i * 3));
+    auto lit3 = std::make_unique<ast::FloatLiteral>(3.f + (i * 3));
+
+    std::vector<std::unique_ptr<ast::Expression>> values;
+    values.push_back(
+        std::make_unique<ast::ConstInitializerExpression>(std::move(lit1)));
+    values.push_back(
+        std::make_unique<ast::ConstInitializerExpression>(std::move(lit2)));
+    values.push_back(
+        std::make_unique<ast::ConstInitializerExpression>(std::move(lit3)));
+
+    ary_values.push_back(std::make_unique<ast::TypeInitializerExpression>(
+        &vec, std::move(values)));
+  }
+
+  ast::TypeInitializerExpression expr(&ary, std::move(ary_values));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
+  EXPECT_EQ(g.result(), std::string("array<vec3<f32>, 3>(") +
+                            "vec3<f32>(1.00000000, 2.00000000, 3.00000000), " +
+                            "vec3<f32>(4.00000000, 5.00000000, 6.00000000), " +
+                            "vec3<f32>(7.00000000, 8.00000000, 9.00000000))");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_test.cc b/src/writer/wgsl/generator_impl_test.cc
index cb05e58..1b0e10a 100644
--- a/src/writer/wgsl/generator_impl_test.cc
+++ b/src/writer/wgsl/generator_impl_test.cc
@@ -14,39 +14,7 @@
 
 #include "src/writer/wgsl/generator_impl.h"
 
-#include <memory>
-#include <utility>
-#include <vector>
-
 #include "gtest/gtest.h"
-#include "src/ast/array_accessor_expression.h"
-#include "src/ast/binding_decoration.h"
-#include "src/ast/bool_literal.h"
-#include "src/ast/builtin.h"
-#include "src/ast/builtin_decoration.h"
-#include "src/ast/decorated_variable.h"
-#include "src/ast/float_literal.h"
-#include "src/ast/identifier_expression.h"
-#include "src/ast/int_literal.h"
-#include "src/ast/location_decoration.h"
-#include "src/ast/set_decoration.h"
-#include "src/ast/struct.h"
-#include "src/ast/struct_member.h"
-#include "src/ast/struct_member_decoration.h"
-#include "src/ast/struct_member_offset_decoration.h"
-#include "src/ast/type/alias_type.h"
-#include "src/ast/type/array_type.h"
-#include "src/ast/type/bool_type.h"
-#include "src/ast/type/f32_type.h"
-#include "src/ast/type/i32_type.h"
-#include "src/ast/type/matrix_type.h"
-#include "src/ast/type/pointer_type.h"
-#include "src/ast/type/struct_type.h"
-#include "src/ast/type/u32_type.h"
-#include "src/ast/type/vector_type.h"
-#include "src/ast/type/void_type.h"
-#include "src/ast/uint_literal.h"
-#include "src/ast/variable.h"
 
 namespace tint {
 namespace writer {
@@ -57,535 +25,6 @@
 
 TEST_F(GeneratorImplTest, DISABLED_Generate) {}
 
-TEST_F(GeneratorImplTest, EmitAliasType_F32) {
-  ast::type::F32Type f32;
-  ast::type::AliasType alias("a", &f32);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitAliasType(&alias)) << g.error();
-  EXPECT_EQ(g.result(), R"(type a = f32;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitAliasType_Struct) {
-  ast::type::I32Type i32;
-  ast::type::F32Type f32;
-
-  std::vector<std::unique_ptr<ast::StructMember>> members;
-  members.push_back(std::make_unique<ast::StructMember>(
-      "a", &f32, std::vector<std::unique_ptr<ast::StructMemberDecoration>>{}));
-
-  std::vector<std::unique_ptr<ast::StructMemberDecoration>> b_deco;
-  b_deco.push_back(std::make_unique<ast::StructMemberOffsetDecoration>(4));
-  members.push_back(
-      std::make_unique<ast::StructMember>("b", &i32, std::move(b_deco)));
-
-  auto str = std::make_unique<ast::Struct>();
-  str->set_members(std::move(members));
-
-  ast::type::StructType s(std::move(str));
-  ast::type::AliasType alias("a", &s);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitAliasType(&alias)) << g.error();
-  EXPECT_EQ(g.result(), R"(type a = struct {
-  a : f32;
-  [[offset 4]] b : i32;
-};
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitEntryPoint_NoName) {
-  ast::EntryPoint ep(ast::PipelineStage::kFragment, "", "frag_main");
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitEntryPoint(&ep)) << g.error();
-  EXPECT_EQ(g.result(), R"(entry_point fragment = frag_main;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitEntryPoint_WithName) {
-  ast::EntryPoint ep(ast::PipelineStage::kFragment, "main", "frag_main");
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitEntryPoint(&ep)) << g.error();
-  EXPECT_EQ(g.result(), R"(entry_point fragment as "main" = frag_main;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitImport) {
-  ast::Import import("GLSL.std.450", "std::glsl");
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitImport(&import)) << g.error();
-  EXPECT_EQ(g.result(), R"(import "GLSL.std.450" as std::glsl;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Alias) {
-  ast::type::F32Type f32;
-  ast::type::AliasType alias("alias", &f32);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&alias)) << g.error();
-  EXPECT_EQ(g.result(), "alias");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Array) {
-  ast::type::BoolType b;
-  ast::type::ArrayType a(&b, 4);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&a)) << g.error();
-  EXPECT_EQ(g.result(), "array<bool, 4>");
-}
-
-TEST_F(GeneratorImplTest, EmitType_RuntimeArray) {
-  ast::type::BoolType b;
-  ast::type::ArrayType a(&b);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&a)) << g.error();
-  EXPECT_EQ(g.result(), "array<bool>");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Bool) {
-  ast::type::BoolType b;
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&b)) << g.error();
-  EXPECT_EQ(g.result(), "bool");
-}
-
-TEST_F(GeneratorImplTest, EmitType_F32) {
-  ast::type::F32Type f32;
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&f32)) << g.error();
-  EXPECT_EQ(g.result(), "f32");
-}
-
-TEST_F(GeneratorImplTest, EmitType_I32) {
-  ast::type::I32Type i32;
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&i32)) << g.error();
-  EXPECT_EQ(g.result(), "i32");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Matrix) {
-  ast::type::F32Type f32;
-  ast::type::MatrixType m(&f32, 3, 2);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&m)) << g.error();
-  EXPECT_EQ(g.result(), "mat2x3<f32>");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Pointer) {
-  ast::type::F32Type f32;
-  ast::type::PointerType p(&f32, ast::StorageClass::kWorkgroup);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&p)) << g.error();
-  EXPECT_EQ(g.result(), "ptr<workgroup, f32>");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Struct) {
-  ast::type::I32Type i32;
-  ast::type::F32Type f32;
-
-  std::vector<std::unique_ptr<ast::StructMember>> members;
-  members.push_back(std::make_unique<ast::StructMember>(
-      "a", &i32, std::vector<std::unique_ptr<ast::StructMemberDecoration>>{}));
-
-  std::vector<std::unique_ptr<ast::StructMemberDecoration>> b_deco;
-  b_deco.push_back(std::make_unique<ast::StructMemberOffsetDecoration>(4));
-  members.push_back(
-      std::make_unique<ast::StructMember>("b", &f32, std::move(b_deco)));
-
-  auto str = std::make_unique<ast::Struct>();
-  str->set_members(std::move(members));
-
-  ast::type::StructType s(std::move(str));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&s)) << g.error();
-  EXPECT_EQ(g.result(), R"(struct {
-  a : i32;
-  [[offset 4]] b : f32;
-})");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Struct_WithDecoration) {
-  ast::type::I32Type i32;
-  ast::type::F32Type f32;
-
-  std::vector<std::unique_ptr<ast::StructMember>> members;
-  members.push_back(std::make_unique<ast::StructMember>(
-      "a", &i32, std::vector<std::unique_ptr<ast::StructMemberDecoration>>{}));
-
-  std::vector<std::unique_ptr<ast::StructMemberDecoration>> b_deco;
-  b_deco.push_back(std::make_unique<ast::StructMemberOffsetDecoration>(4));
-  members.push_back(
-      std::make_unique<ast::StructMember>("b", &f32, std::move(b_deco)));
-
-  auto str = std::make_unique<ast::Struct>();
-  str->set_members(std::move(members));
-  str->set_decoration(ast::StructDecoration::kBlock);
-
-  ast::type::StructType s(std::move(str));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&s)) << g.error();
-  EXPECT_EQ(g.result(), R"([[block]] struct {
-  a : i32;
-  [[offset 4]] b : f32;
-})");
-}
-
-TEST_F(GeneratorImplTest, EmitType_U32) {
-  ast::type::U32Type u32;
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&u32)) << g.error();
-  EXPECT_EQ(g.result(), "u32");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Vector) {
-  ast::type::F32Type f32;
-  ast::type::VectorType v(&f32, 3);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&v)) << g.error();
-  EXPECT_EQ(g.result(), "vec3<f32>");
-}
-
-TEST_F(GeneratorImplTest, EmitType_Void) {
-  ast::type::VoidType v;
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitType(&v)) << g.error();
-  EXPECT_EQ(g.result(), "void");
-}
-
-TEST_F(GeneratorImplTest, EmitVariable) {
-  ast::type::F32Type f32;
-  ast::Variable v("a", ast::StorageClass::kNone, &f32);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
-  EXPECT_EQ(g.result(), R"(var a : f32;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitVariable_StorageClass) {
-  ast::type::F32Type f32;
-  ast::Variable v("a", ast::StorageClass::kInput, &f32);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
-  EXPECT_EQ(g.result(), R"(var<in> a : f32;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitVariable_Decorated) {
-  ast::type::F32Type f32;
-
-  std::vector<std::unique_ptr<ast::VariableDecoration>> decos;
-  decos.push_back(std::make_unique<ast::LocationDecoration>(2));
-
-  ast::DecoratedVariable dv;
-  dv.set_name("a");
-  dv.set_type(&f32);
-  dv.set_decorations(std::move(decos));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitVariable(&dv)) << g.error();
-  EXPECT_EQ(g.result(), R"([[location 2]] var a : f32;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitVariable_Decorated_Multiple) {
-  ast::type::F32Type f32;
-
-  std::vector<std::unique_ptr<ast::VariableDecoration>> decos;
-  decos.push_back(
-      std::make_unique<ast::BuiltinDecoration>(ast::Builtin::kPosition));
-  decos.push_back(std::make_unique<ast::BindingDecoration>(0));
-  decos.push_back(std::make_unique<ast::SetDecoration>(1));
-  decos.push_back(std::make_unique<ast::LocationDecoration>(2));
-
-  ast::DecoratedVariable dv;
-  dv.set_name("a");
-  dv.set_type(&f32);
-  dv.set_decorations(std::move(decos));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitVariable(&dv)) << g.error();
-  EXPECT_EQ(g.result(),
-            R"([[builtin position, binding 0, set 1, location 2]] var a : f32;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitVariable_Initializer) {
-  auto ident = std::make_unique<ast::IdentifierExpression>("initializer");
-
-  ast::type::F32Type f32;
-  ast::Variable v("a", ast::StorageClass::kNone, &f32);
-  v.set_initializer(std::move(ident));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
-  EXPECT_EQ(g.result(), R"(var a : f32 = initializer;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitVariable_Const) {
-  auto ident = std::make_unique<ast::IdentifierExpression>("initializer");
-
-  ast::type::F32Type f32;
-  ast::Variable v("a", ast::StorageClass::kNone, &f32);
-  v.set_initializer(std::move(ident));
-  v.set_is_const(true);
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
-  EXPECT_EQ(g.result(), R"(const a : f32 = initializer;
-)");
-}
-
-TEST_F(GeneratorImplTest, EmitExpression_ArrayAccessor) {
-  auto lit = std::make_unique<ast::IntLiteral>(5);
-  auto idx = std::make_unique<ast::ConstInitializerExpression>(std::move(lit));
-  auto ary = std::make_unique<ast::IdentifierExpression>("ary");
-
-  ast::ArrayAccessorExpression expr(std::move(ary), std::move(idx));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitExpression(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "ary[5]");
-}
-
-TEST_F(GeneratorImplTest, EmitExpression_Identifier) {
-  ast::IdentifierExpression i(std::vector<std::string>{"std", "glsl"});
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitExpression(&i)) << g.error();
-  EXPECT_EQ(g.result(), "std::glsl");
-}
-
-TEST_F(GeneratorImplTest, EmitArrayAccessor) {
-  auto ary = std::make_unique<ast::IdentifierExpression>("ary");
-  auto idx = std::make_unique<ast::IdentifierExpression>("idx");
-
-  ast::ArrayAccessorExpression expr(std::move(ary), std::move(idx));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitArrayAccessor(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "ary[idx]");
-}
-
-TEST_F(GeneratorImplTest, EmitIdentifierExpression_Single) {
-  ast::IdentifierExpression i("glsl");
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitExpression(&i)) << g.error();
-  EXPECT_EQ(g.result(), "glsl");
-}
-
-TEST_F(GeneratorImplTest, EmitIdentifierExpression_MultipleNames) {
-  ast::IdentifierExpression i({"std", "glsl", "init"});
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitExpression(&i)) << g.error();
-  EXPECT_EQ(g.result(), "std::glsl::init");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Bool) {
-  auto lit = std::make_unique<ast::BoolLiteral>(false);
-  ast::ConstInitializerExpression expr(std::move(lit));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "false");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Int) {
-  auto lit = std::make_unique<ast::IntLiteral>(-12345);
-  ast::ConstInitializerExpression expr(std::move(lit));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "-12345");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_UInt) {
-  auto lit = std::make_unique<ast::UintLiteral>(56779);
-  ast::ConstInitializerExpression expr(std::move(lit));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "56779u");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Float) {
-  auto lit = std::make_unique<ast::FloatLiteral>(1.5e27);
-  ast::ConstInitializerExpression expr(std::move(lit));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "1.49999995e+27");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Float) {
-  ast::type::F32Type f32;
-
-  auto lit = std::make_unique<ast::FloatLiteral>(-1.2e-5);
-  std::vector<std::unique_ptr<ast::Expression>> values;
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
-
-  ast::TypeInitializerExpression expr(&f32, std::move(values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "f32(-1.20000004e-05)");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Bool) {
-  ast::type::BoolType b;
-
-  auto lit = std::make_unique<ast::BoolLiteral>(true);
-  std::vector<std::unique_ptr<ast::Expression>> values;
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
-
-  ast::TypeInitializerExpression expr(&b, std::move(values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "bool(true)");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Int) {
-  ast::type::I32Type i32;
-
-  auto lit = std::make_unique<ast::IntLiteral>(-12345);
-  std::vector<std::unique_ptr<ast::Expression>> values;
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
-
-  ast::TypeInitializerExpression expr(&i32, std::move(values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "i32(-12345)");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Uint) {
-  ast::type::U32Type u32;
-
-  auto lit = std::make_unique<ast::UintLiteral>(12345);
-  std::vector<std::unique_ptr<ast::Expression>> values;
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit)));
-
-  ast::TypeInitializerExpression expr(&u32, std::move(values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "u32(12345u)");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Vec) {
-  ast::type::F32Type f32;
-  ast::type::VectorType vec(&f32, 3);
-
-  auto lit1 = std::make_unique<ast::FloatLiteral>(1.f);
-  auto lit2 = std::make_unique<ast::FloatLiteral>(2.f);
-  auto lit3 = std::make_unique<ast::FloatLiteral>(3.f);
-  std::vector<std::unique_ptr<ast::Expression>> values;
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit1)));
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit2)));
-  values.push_back(
-      std::make_unique<ast::ConstInitializerExpression>(std::move(lit3)));
-
-  ast::TypeInitializerExpression expr(&vec, std::move(values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), "vec3<f32>(1.00000000, 2.00000000, 3.00000000)");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Mat) {
-  ast::type::F32Type f32;
-  ast::type::MatrixType mat(&f32, 3, 2);
-
-  ast::type::VectorType vec(&f32, 2);
-
-  std::vector<std::unique_ptr<ast::Expression>> mat_values;
-
-  for (size_t i = 0; i < 3; i++) {
-    auto lit1 = std::make_unique<ast::FloatLiteral>(1.f + (i * 2));
-    auto lit2 = std::make_unique<ast::FloatLiteral>(2.f + (i * 2));
-
-    std::vector<std::unique_ptr<ast::Expression>> values;
-    values.push_back(
-        std::make_unique<ast::ConstInitializerExpression>(std::move(lit1)));
-    values.push_back(
-        std::make_unique<ast::ConstInitializerExpression>(std::move(lit2)));
-
-    mat_values.push_back(std::make_unique<ast::TypeInitializerExpression>(
-        &vec, std::move(values)));
-  }
-
-  ast::TypeInitializerExpression expr(&mat, std::move(mat_values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(),
-            std::string("mat2x3<f32>(vec2<f32>(1.00000000, 2.00000000), ") +
-                "vec2<f32>(3.00000000, 4.00000000), " +
-                "vec2<f32>(5.00000000, 6.00000000))");
-}
-
-TEST_F(GeneratorImplTest, EmitInitializer_Type_Array) {
-  ast::type::F32Type f32;
-  ast::type::VectorType vec(&f32, 3);
-  ast::type::ArrayType ary(&vec, 3);
-
-  std::vector<std::unique_ptr<ast::Expression>> ary_values;
-
-  for (size_t i = 0; i < 3; i++) {
-    auto lit1 = std::make_unique<ast::FloatLiteral>(1.f + (i * 3));
-    auto lit2 = std::make_unique<ast::FloatLiteral>(2.f + (i * 3));
-    auto lit3 = std::make_unique<ast::FloatLiteral>(3.f + (i * 3));
-
-    std::vector<std::unique_ptr<ast::Expression>> values;
-    values.push_back(
-        std::make_unique<ast::ConstInitializerExpression>(std::move(lit1)));
-    values.push_back(
-        std::make_unique<ast::ConstInitializerExpression>(std::move(lit2)));
-    values.push_back(
-        std::make_unique<ast::ConstInitializerExpression>(std::move(lit3)));
-
-    ary_values.push_back(std::make_unique<ast::TypeInitializerExpression>(
-        &vec, std::move(values)));
-  }
-
-  ast::TypeInitializerExpression expr(&ary, std::move(ary_values));
-
-  GeneratorImpl g;
-  ASSERT_TRUE(g.EmitInitializer(&expr)) << g.error();
-  EXPECT_EQ(g.result(), std::string("array<vec3<f32>, 3>(") +
-                            "vec3<f32>(1.00000000, 2.00000000, 3.00000000), " +
-                            "vec3<f32>(4.00000000, 5.00000000, 6.00000000), " +
-                            "vec3<f32>(7.00000000, 8.00000000, 9.00000000))");
-}
-
 }  // namespace
 }  // namespace wgsl
 }  // namespace writer
diff --git a/src/writer/wgsl/generator_impl_type_test.cc b/src/writer/wgsl/generator_impl_type_test.cc
new file mode 100644
index 0000000..86e2489
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_type_test.cc
@@ -0,0 +1,190 @@
+// 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.
+
+#include "gtest/gtest.h"
+#include "src/ast/struct.h"
+#include "src/ast/struct_decoration.h"
+#include "src/ast/struct_member.h"
+#include "src/ast/struct_member_decoration.h"
+#include "src/ast/struct_member_offset_decoration.h"
+#include "src/ast/type/array_type.h"
+#include "src/ast/type/bool_type.h"
+#include "src/ast/type/f32_type.h"
+#include "src/ast/type/i32_type.h"
+#include "src/ast/type/matrix_type.h"
+#include "src/ast/type/pointer_type.h"
+#include "src/ast/type/struct_type.h"
+#include "src/ast/type/u32_type.h"
+#include "src/ast/type/vector_type.h"
+#include "src/ast/type/void_type.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitType_Alias) {
+  ast::type::F32Type f32;
+  ast::type::AliasType alias("alias", &f32);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&alias)) << g.error();
+  EXPECT_EQ(g.result(), "alias");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Array) {
+  ast::type::BoolType b;
+  ast::type::ArrayType a(&b, 4);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&a)) << g.error();
+  EXPECT_EQ(g.result(), "array<bool, 4>");
+}
+
+TEST_F(GeneratorImplTest, EmitType_RuntimeArray) {
+  ast::type::BoolType b;
+  ast::type::ArrayType a(&b);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&a)) << g.error();
+  EXPECT_EQ(g.result(), "array<bool>");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Bool) {
+  ast::type::BoolType b;
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&b)) << g.error();
+  EXPECT_EQ(g.result(), "bool");
+}
+
+TEST_F(GeneratorImplTest, EmitType_F32) {
+  ast::type::F32Type f32;
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&f32)) << g.error();
+  EXPECT_EQ(g.result(), "f32");
+}
+
+TEST_F(GeneratorImplTest, EmitType_I32) {
+  ast::type::I32Type i32;
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&i32)) << g.error();
+  EXPECT_EQ(g.result(), "i32");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Matrix) {
+  ast::type::F32Type f32;
+  ast::type::MatrixType m(&f32, 3, 2);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&m)) << g.error();
+  EXPECT_EQ(g.result(), "mat2x3<f32>");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Pointer) {
+  ast::type::F32Type f32;
+  ast::type::PointerType p(&f32, ast::StorageClass::kWorkgroup);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&p)) << g.error();
+  EXPECT_EQ(g.result(), "ptr<workgroup, f32>");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Struct) {
+  ast::type::I32Type i32;
+  ast::type::F32Type f32;
+
+  std::vector<std::unique_ptr<ast::StructMember>> members;
+  members.push_back(std::make_unique<ast::StructMember>(
+      "a", &i32, std::vector<std::unique_ptr<ast::StructMemberDecoration>>{}));
+
+  std::vector<std::unique_ptr<ast::StructMemberDecoration>> b_deco;
+  b_deco.push_back(std::make_unique<ast::StructMemberOffsetDecoration>(4));
+  members.push_back(
+      std::make_unique<ast::StructMember>("b", &f32, std::move(b_deco)));
+
+  auto str = std::make_unique<ast::Struct>();
+  str->set_members(std::move(members));
+
+  ast::type::StructType s(std::move(str));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&s)) << g.error();
+  EXPECT_EQ(g.result(), R"(struct {
+  a : i32;
+  [[offset 4]] b : f32;
+})");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Struct_WithDecoration) {
+  ast::type::I32Type i32;
+  ast::type::F32Type f32;
+
+  std::vector<std::unique_ptr<ast::StructMember>> members;
+  members.push_back(std::make_unique<ast::StructMember>(
+      "a", &i32, std::vector<std::unique_ptr<ast::StructMemberDecoration>>{}));
+
+  std::vector<std::unique_ptr<ast::StructMemberDecoration>> b_deco;
+  b_deco.push_back(std::make_unique<ast::StructMemberOffsetDecoration>(4));
+  members.push_back(
+      std::make_unique<ast::StructMember>("b", &f32, std::move(b_deco)));
+
+  auto str = std::make_unique<ast::Struct>();
+  str->set_members(std::move(members));
+  str->set_decoration(ast::StructDecoration::kBlock);
+
+  ast::type::StructType s(std::move(str));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&s)) << g.error();
+  EXPECT_EQ(g.result(), R"([[block]] struct {
+  a : i32;
+  [[offset 4]] b : f32;
+})");
+}
+
+TEST_F(GeneratorImplTest, EmitType_U32) {
+  ast::type::U32Type u32;
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&u32)) << g.error();
+  EXPECT_EQ(g.result(), "u32");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Vector) {
+  ast::type::F32Type f32;
+  ast::type::VectorType v(&f32, 3);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&v)) << g.error();
+  EXPECT_EQ(g.result(), "vec3<f32>");
+}
+
+TEST_F(GeneratorImplTest, EmitType_Void) {
+  ast::type::VoidType v;
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitType(&v)) << g.error();
+  EXPECT_EQ(g.result(), "void");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint
diff --git a/src/writer/wgsl/generator_impl_variable_test.cc b/src/writer/wgsl/generator_impl_variable_test.cc
new file mode 100644
index 0000000..06463e8
--- /dev/null
+++ b/src/writer/wgsl/generator_impl_variable_test.cc
@@ -0,0 +1,124 @@
+// 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.
+
+#include <memory>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "src/ast/binding_decoration.h"
+#include "src/ast/builtin_decoration.h"
+#include "src/ast/decorated_variable.h"
+#include "src/ast/location_decoration.h"
+#include "src/ast/set_decoration.h"
+#include "src/ast/type/f32_type.h"
+#include "src/ast/variable_decoration.h"
+#include "src/writer/wgsl/generator_impl.h"
+
+namespace tint {
+namespace writer {
+namespace wgsl {
+namespace {
+
+using GeneratorImplTest = testing::Test;
+
+TEST_F(GeneratorImplTest, EmitVariable) {
+  ast::type::F32Type f32;
+  ast::Variable v("a", ast::StorageClass::kNone, &f32);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
+  EXPECT_EQ(g.result(), R"(var a : f32;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitVariable_StorageClass) {
+  ast::type::F32Type f32;
+  ast::Variable v("a", ast::StorageClass::kInput, &f32);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
+  EXPECT_EQ(g.result(), R"(var<in> a : f32;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitVariable_Decorated) {
+  ast::type::F32Type f32;
+
+  std::vector<std::unique_ptr<ast::VariableDecoration>> decos;
+  decos.push_back(std::make_unique<ast::LocationDecoration>(2));
+
+  ast::DecoratedVariable dv;
+  dv.set_name("a");
+  dv.set_type(&f32);
+  dv.set_decorations(std::move(decos));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitVariable(&dv)) << g.error();
+  EXPECT_EQ(g.result(), R"([[location 2]] var a : f32;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitVariable_Decorated_Multiple) {
+  ast::type::F32Type f32;
+
+  std::vector<std::unique_ptr<ast::VariableDecoration>> decos;
+  decos.push_back(
+      std::make_unique<ast::BuiltinDecoration>(ast::Builtin::kPosition));
+  decos.push_back(std::make_unique<ast::BindingDecoration>(0));
+  decos.push_back(std::make_unique<ast::SetDecoration>(1));
+  decos.push_back(std::make_unique<ast::LocationDecoration>(2));
+
+  ast::DecoratedVariable dv;
+  dv.set_name("a");
+  dv.set_type(&f32);
+  dv.set_decorations(std::move(decos));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitVariable(&dv)) << g.error();
+  EXPECT_EQ(g.result(),
+            R"([[builtin position, binding 0, set 1, location 2]] var a : f32;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitVariable_Initializer) {
+  auto ident = std::make_unique<ast::IdentifierExpression>("initializer");
+
+  ast::type::F32Type f32;
+  ast::Variable v("a", ast::StorageClass::kNone, &f32);
+  v.set_initializer(std::move(ident));
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
+  EXPECT_EQ(g.result(), R"(var a : f32 = initializer;
+)");
+}
+
+TEST_F(GeneratorImplTest, EmitVariable_Const) {
+  auto ident = std::make_unique<ast::IdentifierExpression>("initializer");
+
+  ast::type::F32Type f32;
+  ast::Variable v("a", ast::StorageClass::kNone, &f32);
+  v.set_initializer(std::move(ident));
+  v.set_is_const(true);
+
+  GeneratorImpl g;
+  ASSERT_TRUE(g.EmitVariable(&v)) << g.error();
+  EXPECT_EQ(g.result(), R"(const a : f32 = initializer;
+)");
+}
+
+}  // namespace
+}  // namespace wgsl
+}  // namespace writer
+}  // namespace tint