Add optional public header checking to GN build

tools/gn/header_checker_unittest.cc

Index: tools/gn/header_checker_unittest.cc
diff --git a/tools/gn/header_checker_unittest.cc b/tools/gn/header_checker_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..90e4165529c8db9be36a9b240ce351d72a1718b8
--- /dev/null
+++ b/tools/gn/header_checker_unittest.cc
@@ -0,0 +1,102 @@
+// 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 <vector>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "tools/gn/header_checker.h"
+#include "tools/gn/scheduler.h"
+#include "tools/gn/target.h"
+#include "tools/gn/test_with_scope.h"
+
+namespace {
+
+class HeaderCheckerTest : public testing::Test {
+ public:
+  HeaderCheckerTest()
+      : a_(setup_.settings(), Label(SourceDir("//"), "a")),
+        b_(setup_.settings(), Label(SourceDir("//"), "a")),
+        c_(setup_.settings(), Label(SourceDir("//"), "c")) {
+    a_.deps().push_back(LabelTargetPair(&b_));
+    b_.deps().push_back(LabelTargetPair(&c_));
+
+    targets_.push_back(&a_);
+    targets_.push_back(&b_);
+    targets_.push_back(&c_);
+  }
+
+ protected:
+  Scheduler scheduler_;
+
+  TestWithScope setup_;
+
+  // Some headers that are automatically set up with a dependency chain.
+  // a -> b -> c
+  Target a_;
+  Target b_;
+  Target c_;
+
+  std::vector<const Target*> targets_;
+};
+
+}  // namespace
+
+TEST_F(HeaderCheckerTest, IsDependencyOf) {
+  scoped_refptr<HeaderChecker> checker(
+      new HeaderChecker(setup_.build_settings(), targets_));
+
+  EXPECT_FALSE(checker->IsDependencyOf(&a_, &a_));
+  EXPECT_TRUE(checker->IsDependencyOf(&b_, &a_));
+  EXPECT_TRUE(checker->IsDependencyOf(&c_, &a_));
+  EXPECT_FALSE(checker->IsDependencyOf(&a_, &c_));
+}
+
+TEST_F(HeaderCheckerTest, CheckInclude) {
+  // Add a disconnected target d with a header to check that you have to have
+  // to depend on a target listing a header.
+  Target d(setup_.settings(), Label(SourceDir("//"), "d"));
+  SourceFile d_header("//d_header.h");
+  d.sources().push_back(SourceFile(d_header));
+
+  // Add a header on B and say everything in B is public.
+  SourceFile b_public("//b_public.h");
+  b_.sources().push_back(b_public);
+  c_.set_all_headers_public(true);
+
+  // Add a public and private header on C.
+  SourceFile c_public("//c_public.h");
+  SourceFile c_private("//c_private.h");
+  c_.sources().push_back(c_private);
+  c_.public_headers().push_back(c_public);
+  c_.set_all_headers_public(false);
+
+  targets_.push_back(&d);
+  scoped_refptr<HeaderChecker> checker(
+      new HeaderChecker(setup_.build_settings(), targets_));
+
+  // A file in target A can't include a header from D because A has no
+  // dependency on D.
+  Err err;
+  SourceFile source_file("//some_file.cc");
+  EXPECT_FALSE(checker->CheckInclude(&a_, source_file, d_header, &err));
+  EXPECT_TRUE(err.has_error());
+
+  // A can include the public header in B.
+  err = Err();
+  EXPECT_TRUE(checker->CheckInclude(&a_, source_file, b_public, &err));
+  EXPECT_FALSE(err.has_error());
+
+  // Check A depending on the public and private headers in C.
+  err = Err();
+  EXPECT_TRUE(checker->CheckInclude(&a_, source_file, c_public, &err));
+  EXPECT_FALSE(err.has_error());
+  EXPECT_FALSE(checker->CheckInclude(&a_, source_file, c_private, &err));
+  EXPECT_TRUE(err.has_error());
+
+  // A can depend on a random file unknown to the build.
+  err = Err();
+  EXPECT_TRUE(checker->CheckInclude(&a_, source_file, SourceFile("//random.h"),
+                                    &err));
+  EXPECT_FALSE(err.has_error());
+}