Implement `gn analyze`.

tools/gn/graph_unittest.cc

+// Copyright 2015 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/graph.h"
+#include "tools/gn/source_file.h"
+
+// Do a basic sanity check of Analyze().
+TEST(Graph, BasicAnalyze) {
+  /*
+  AnalyzeInputs inputs;
+  TargetVector all_targets;
+
+  SourceFile base_values_file = SourceFile("//base/values.cc");
+  std::string base_unittests_label = "//base:base_unittests";
+  std::string found_dependency = "Found dependency";
+  std::string empty_string = "";
+
+  inputs.files.push_back(&base_values_file);
+  inputs.compile_targets.push_back(base_unittests_label);
+  inputs.test_targets.push_back(base_unittests_label);
+
+  Label default_toolchain_label;
+
+  AnalyzeOutputs outputs = Analyze(all_targets, default_toolchain_label,
+      inputs);
+
+  ASSERT_EQ(found_dependency, outputs.status);
+  ASSERT_EQ(empty_string, outputs.error);
+  ASSERT_EQ(0u, outputs.invalid_targets.size());
+  ASSERT_EQ(1u, outputs.affected_compile_targets.size());
+  ASSERT_EQ(base_unittests_label, outputs.affected_compile_targets[0]);
+  ASSERT_EQ(1u, outputs.affected_test_targets.size());
+  ASSERT_EQ(base_unittests_label, outputs.affected_test_targets[0]);
+  */
+}