Add "." accessors to GN.

tools/gn/parse_tree_unittest.cc

+// Copyright 2014 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"
+
+TEST(ParseTree, Accessor) {
+  TestWithScope setup;
+
+  // Make a pretend parse node with proper tracking that we can blame for the
+  // given value.
+  InputFile input_file(SourceFile("//foo"));
+  Token base_token(Location(&input_file, 1, 1), Token::IDENTIFIER, "a");
+  Token member_token(Location(&input_file, 1, 1), Token::IDENTIFIER, "b");
+
+  AccessorNode accessor;
+  accessor.set_base(base_token);
+
+  scoped_ptr<IdentifierNode> member_identifier(
+      new IdentifierNode(member_token));
+  accessor.set_member(member_identifier.Pass());
+
+  // The access should fail because a is not defined.
+  Err err;
+  Value result = accessor.Execute(setup.scope(), &err);
+  EXPECT_TRUE(err.has_error());
+  EXPECT_EQ(Value::NONE, result.type());
+
+  // Define a as a Scope. It should still fail because b isn't defined.
+  Scope a_scope(setup.scope());
+  err = Err();
+  setup.scope()->SetValue("a", Value(NULL, &a_scope), NULL);
+  result = accessor.Execute(setup.scope(), &err);
+  EXPECT_TRUE(err.has_error());
+  EXPECT_EQ(Value::NONE, result.type());
+
+  // Define b, accessor should succeed now.
+  const int64 kBValue = 42;
+  err = Err();
+  a_scope.SetValue("b", Value(NULL, kBValue), NULL);
+  result = accessor.Execute(setup.scope(), &err);
+  EXPECT_FALSE(err.has_error());
+  ASSERT_EQ(Value::INTEGER, result.type());
+  EXPECT_EQ(kBValue, result.int_value());
+}