Add initial prototype for the GN meta-buildsystem.

tools/gn/ninja_helper_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/filesystem_utils.h"
+#include "tools/gn/ninja_helper.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/target.h"
+#include "tools/gn/toolchain.h"
+
+namespace {
+
+class HelperSetterUpper {
+ public:
+  HelperSetterUpper()
+      : build_settings(),
+        toolchain(Label(SourceDir("//"), "tc", SourceDir(), std::string())),
+        settings(&build_settings, &toolchain, std::string()),
+        target(&settings,
+               Label(SourceDir("//tools/gn/"), "name",
+                     SourceDir(), std::string())) {
+    settings.set_target_os(Settings::WIN);
+
+    // Output going to "out/Debug".
+    build_settings.SetBuildDir(SourceDir("/out/Debug/"));
+
+    // Our source target is in "tools/gn".
+    target.set_output_type(Target::EXECUTABLE);
+  }
+
+  BuildSettings build_settings;
+  Toolchain toolchain;
+  Settings settings;
+  Target target;
+};
+
+}  // namespace
+
+TEST(NinjaHelper, GetNinjaFileForTarget) {
+  HelperSetterUpper setup;
+  NinjaHelper helper(&setup.build_settings);
+
+  // Default toolchain.
+  EXPECT_EQ(OutputFile("obj/tools/gn/name.ninja").value(),
+            helper.GetNinjaFileForTarget(&setup.target).value());
+}
+
+TEST(NinjaHelper, GetOutputFileForSource) {
+  HelperSetterUpper setup;
+  NinjaHelper helper(&setup.build_settings);
+
+  // On Windows, expect ".obj"
+  EXPECT_EQ(OutputFile("obj/tools/gn/name.foo.obj").value(),
+            helper.GetOutputFileForSource(&setup.target,
+                                          SourceFile("//tools/gn/foo.cc"),
+                                          SOURCE_CC).value());
+}
+
+TEST(NinjaHelper, GetTargetOutputFile) {
+  HelperSetterUpper setup;
+  NinjaHelper helper(&setup.build_settings);
+  EXPECT_EQ(OutputFile("name.exe"),
+            helper.GetTargetOutputFile(&setup.target));
+
+  // Static library on Windows goes alongside the object files.
+  setup.target.set_output_type(Target::STATIC_LIBRARY);
+  EXPECT_EQ(OutputFile("obj/tools/gn/name.lib"),
+            helper.GetTargetOutputFile(&setup.target));
+
+  // TODO(brettw) test output to library and other OS types.
+}