Add "." accessors to GN.

tools/gn/scope_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
 #include "tools/gn/test_with_scope.h"
 
@@ skipping 28 matching lines @@
     Scope new_scope(setup.settings());
     Value new_value(&assignment, "hello");
     new_scope.SetValue("v", new_value, &assignment);
 
     Err err;
     EXPECT_TRUE(new_scope.NonRecursiveMergeTo(
         setup.scope(), &assignment, "error", &err));
     EXPECT_FALSE(err.has_error());
   }
 }
+
+TEST(Scope, GetMutableValue) {
+  TestWithScope setup;
+
+  // Make a pretend parse node with proper tracking that we can blame for the
+  // given value.
+  InputFile input_file(SourceFile("//foo"));
+  Token assignment_token(Location(&input_file, 1, 1), Token::STRING,
+      "\"hello\"");
+  LiteralNode assignment;
+  assignment.set_value(assignment_token);
+
+  const char kOnConst[] = "on_const";
+  const char kOnMutable1[] = "on_mutable1";
+  const char kOnMutable2[] = "on_mutable2";
+
+  Value value(&assignment, "hello");
+
+  // Create a root scope with one value.
+  Scope root_scope(setup.settings());
+  root_scope.SetValue(kOnConst, value, &assignment);
+
+  // Create a first nested scope with a different value.
+  const Scope* const_root_scope = &root_scope;
+  Scope mutable_scope1(const_root_scope);
+  mutable_scope1.SetValue(kOnMutable1, value, &assignment);
+
+  // Create a second nested scope with a different value.
+  Scope mutable_scope2(&mutable_scope1);
+  mutable_scope2.SetValue(kOnMutable2, value, &assignment);
+
+  // Check getting root scope values.
+  EXPECT_TRUE(mutable_scope2.GetValue(kOnConst, true));
+  EXPECT_FALSE(mutable_scope2.GetMutableValue(kOnConst, true));
+
+  // Test reading a value from scope 1.
+  Value* mutable1_result = mutable_scope2.GetMutableValue(kOnMutable1, false);
+  ASSERT_TRUE(mutable1_result);
+  EXPECT_TRUE(*mutable1_result == value);
+
+  // Make sure CheckForUnusedVars works on scope1 (we didn't mark the value as
+  // used in the previous step).
+  Err err;
+  EXPECT_FALSE(mutable_scope1.CheckForUnusedVars(&err));
+  mutable1_result = mutable_scope2.GetMutableValue(kOnMutable1, true);
+  EXPECT_TRUE(mutable1_result);
+  err = Err();
+  EXPECT_TRUE(mutable_scope1.CheckForUnusedVars(&err));
+
+  // Test reading a value from scope 2.
+  Value* mutable2_result = mutable_scope2.GetMutableValue(kOnMutable2, true);
+  ASSERT_TRUE(mutable2_result);
+  EXPECT_TRUE(*mutable2_result == value);
+}