Add test for call expression

This CL adds unit tests for the call expression. The IsValid method is
extended to verify none of the provided parameters are a nullptr.

Change-Id: I5dfd3ec1f086ef02ab965218a1d8610a1c212628
Bug: tint:11
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/16360
Reviewed-by: Sarah Mashayekhi <sarahmashay@google.com>
Commit-Queue: Sarah Mashayekhi <sarahmashay@google.com>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 2a6a9be..0434df8 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -200,6 +200,7 @@
   ast/bool_literal_test.cc
   ast/break_statement_test.cc
   ast/builtin_decoration_test.cc
+  ast/call_expression_test.cc
   ast/entry_point_test.cc
   ast/import_test.cc
   ast/int_literal_test.cc
diff --git a/src/ast/call_expression.cc b/src/ast/call_expression.cc
index 4b0d97d..6dad233 100644
--- a/src/ast/call_expression.cc
+++ b/src/ast/call_expression.cc
@@ -17,6 +17,8 @@
 namespace tint {
 namespace ast {
 
+CallExpression::CallExpression() : Expression() {}
+
 CallExpression::CallExpression(std::unique_ptr<Expression> func,
                                std::vector<std::unique_ptr<Expression>> params)
     : Expression(), func_(std::move(func)), params_(std::move(params)) {}
@@ -29,11 +31,22 @@
 CallExpression::~CallExpression() = default;
 
 bool CallExpression::IsValid() const {
-  return func_ != nullptr;
+  if (func_ == nullptr || !func_->IsValid())
+    return false;
+
+  // All params must be valid
+  for (const auto& param : params_) {
+    if (param == nullptr || !param->IsValid())
+      return false;
+  }
+  return true;
 }
 
 void CallExpression::to_str(std::ostream& out, size_t indent) const {
-  func_->to_str(out, indent);
+  make_indent(out, indent);
+  out << "Call{" << std::endl;
+  func_->to_str(out, indent + 2);
+
   make_indent(out, indent + 2);
   out << "(" << std::endl;
   for (const auto& param : params_)
@@ -41,6 +54,9 @@
 
   make_indent(out, indent + 2);
   out << ")" << std::endl;
+
+  make_indent(out, indent);
+  out << "}" << std::endl;
 }
 
 }  // namespace ast
diff --git a/src/ast/call_expression.h b/src/ast/call_expression.h
index ac5178f..0644d69 100644
--- a/src/ast/call_expression.h
+++ b/src/ast/call_expression.h
@@ -29,6 +29,8 @@
 class CallExpression : public Expression {
  public:
   /// Constructor
+  CallExpression();
+  /// Constructor
   /// @param func the function
   /// @param params the parameters
   CallExpression(std::unique_ptr<Expression> func,
diff --git a/src/ast/call_expression_test.cc b/src/ast/call_expression_test.cc
new file mode 100644
index 0000000..b4dad2f
--- /dev/null
+++ b/src/ast/call_expression_test.cc
@@ -0,0 +1,131 @@
+// 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 "src/ast/call_expression.h"
+
+#include "gtest/gtest.h"
+#include "src/ast/identifier_expression.h"
+
+namespace tint {
+namespace ast {
+
+using CallExpressionTest = testing::Test;
+
+TEST_F(CallExpressionTest, Creation) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  std::vector<std::unique_ptr<Expression>> params;
+  params.push_back(std::make_unique<IdentifierExpression>("param1"));
+  params.push_back(std::make_unique<IdentifierExpression>("param2"));
+
+  auto func_ptr = func.get();
+  auto param1_ptr = params[0].get();
+  auto param2_ptr = params[1].get();
+
+  CallExpression stmt(std::move(func), std::move(params));
+  EXPECT_EQ(stmt.func(), func_ptr);
+
+  const auto& vec = stmt.params();
+  ASSERT_EQ(vec.size(), 2);
+  EXPECT_EQ(vec[0].get(), param1_ptr);
+  EXPECT_EQ(vec[1].get(), param2_ptr);
+}
+
+TEST_F(CallExpressionTest, Creation_WithSource) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  CallExpression stmt(Source{20, 2}, std::move(func), {});
+  auto src = stmt.source();
+  EXPECT_EQ(src.line, 20);
+  EXPECT_EQ(src.column, 2);
+}
+
+TEST_F(CallExpressionTest, IsCall) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  CallExpression stmt(std::move(func), {});
+  EXPECT_TRUE(stmt.IsCall());
+}
+
+TEST_F(CallExpressionTest, IsValid) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  CallExpression stmt(std::move(func), {});
+  EXPECT_TRUE(stmt.IsValid());
+}
+
+TEST_F(CallExpressionTest, IsValid_MissingFunction) {
+  CallExpression stmt;
+  EXPECT_FALSE(stmt.IsValid());
+}
+
+TEST_F(CallExpressionTest, IsValid_NullParam) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  std::vector<std::unique_ptr<Expression>> params;
+  params.push_back(std::make_unique<IdentifierExpression>("param1"));
+  params.push_back(nullptr);
+  params.push_back(std::make_unique<IdentifierExpression>("param2"));
+
+  CallExpression stmt(std::move(func), std::move(params));
+  EXPECT_FALSE(stmt.IsValid());
+}
+
+TEST_F(CallExpressionTest, IsValid_InvalidFunction) {
+  auto func = std::make_unique<IdentifierExpression>("");
+  std::vector<std::unique_ptr<Expression>> params;
+  params.push_back(std::make_unique<IdentifierExpression>("param1"));
+
+  CallExpression stmt(std::move(func), std::move(params));
+  EXPECT_FALSE(stmt.IsValid());
+}
+
+TEST_F(CallExpressionTest, IsValid_InvalidParam) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  std::vector<std::unique_ptr<Expression>> params;
+  params.push_back(std::make_unique<IdentifierExpression>(""));
+
+  CallExpression stmt(std::move(func), std::move(params));
+  EXPECT_FALSE(stmt.IsValid());
+}
+
+TEST_F(CallExpressionTest, ToStr_NoParams) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  CallExpression stmt(std::move(func), {});
+  std::ostringstream out;
+  stmt.to_str(out, 2);
+  EXPECT_EQ(out.str(), R"(  Call{
+    Identifier{func}
+    (
+    )
+  }
+)");
+}
+
+TEST_F(CallExpressionTest, ToStr_WithParams) {
+  auto func = std::make_unique<IdentifierExpression>("func");
+  std::vector<std::unique_ptr<Expression>> params;
+  params.push_back(std::make_unique<IdentifierExpression>("param1"));
+  params.push_back(std::make_unique<IdentifierExpression>("param2"));
+
+  CallExpression stmt(std::move(func), std::move(params));
+  std::ostringstream out;
+  stmt.to_str(out, 2);
+  EXPECT_EQ(out.str(), R"(  Call{
+    Identifier{func}
+    (
+      Identifier{param1}
+      Identifier{param2}
+    )
+  }
+)");
+}
+
+}  // namespace ast
+}  // namespace tint