Add tests for NopStatement.

This CL adds tests for the NopStatement AST node.

Bug: tint:11
Change-Id: I890b7f6bc6347ba4f5a67334385feffd24079d5d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/16665
Reviewed-by: Sarah Mashayekhi <sarahmashay@google.com>

src/CMakeLists.txt

@@ -224,6 +224,7 @@ set(TINT_TEST_SRCS
   ast/loop_statement_test.cc
   ast/member_accessor_expression_test.cc
   ast/module_test.cc
+  ast/nop_statement_test.cc
   ast/set_decoration_test.cc
   ast/struct_member_test.cc
   ast/struct_member_offset_decoration_test.cc

src/ast/nop_statement_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 "src/ast/nop_statement.h"
+
+#include <sstream>
+
+#include "gtest/gtest.h"
+
+namespace tint {
+namespace ast {
+
+using NopStatementTest = testing::Test;
+
+TEST_F(NopStatementTest, Creation) {
+  NopStatement n;
+  EXPECT_EQ(n.line(), 0);
+  EXPECT_EQ(n.column(), 0);
+}
+
+TEST_F(NopStatementTest, Creation_WithSource) {
+  NopStatement n(Source{20, 2});
+  EXPECT_EQ(n.line(), 20);
+  EXPECT_EQ(n.column(), 2);
+}
+
+TEST_F(NopStatementTest, IsNop) {
+  NopStatement n;
+  EXPECT_TRUE(n.IsNop());
+}
+
+TEST_F(NopStatementTest, IsValid) {
+  NopStatement n;
+  EXPECT_TRUE(n.IsValid());
+}
+
+TEST_F(NopStatementTest, ToStr) {
+  NopStatement n;
+  std::ostringstream out;
+  n.to_str(out, 2);
+  EXPECT_EQ(out.str(), R"(  Nop{}
+)");
+}
+
+}  // namespace ast
+}  // namespace tint