GN: Use build directory for CD for scripts

tools/gn/test_with_scope.h

+// 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.
+
+#ifndef TOOLS_GN_TEST_WITH_SCOPE_H_
+#define TOOLS_GN_TEST_WITH_SCOPE_H_
+
+#include "base/basictypes.h"
+#include "tools/gn/build_settings.h"
+#include "tools/gn/scope.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/toolchain.h"
+
+// A helper class for setting up a Scope that a test can use. It makes a
+// toolchain and sets up all the build state.
+class TestWithScope {
+ public:
+  TestWithScope();
+  ~TestWithScope();
+
+  BuildSettings* build_settings() { return &build_settings_; }
+  Settings* settings() { return &settings_; }
+  Scope* scope() { return &scope_; }
+
+ private:
+  BuildSettings build_settings_;
+  Toolchain toolchain_;
+  Settings settings_;
+  Scope scope_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestWithScope);
+};
+
+#endif  // TOOLS_GN_TEST_WITH_SCOPE_H_