Refactor GN source expansions.

tools/gn/action_target_generator_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/scheduler.h"
+#include "tools/gn/test_with_scope.h"
+
+// Tests that actions can't have output substitutions.
+TEST(ActionTargetGenerator, ActionOutputSubstitutions) {
+  Scheduler scheduler;
+  TestWithScope setup;
+  Scope::ItemVector items_;
+  setup.scope()->set_item_collector(&items_);
+
+  // First test one with no substitutions, this should be valid.
+  TestParseInput input_good(
+      "action(\"foo\") {\n"
+      "  script = \"//foo.py\"\n"
+      "  sources = [ \"//bar.txt\" ]\n"
+      "  outputs = [ \"//out/Debug/one.txt\" ]\n"
+      "}");
+  ASSERT_FALSE(input_good.has_error());
+
+  // This should run fine.
+  Err err;
+  input_good.parsed()->Execute(setup.scope(), &err);
+  ASSERT_FALSE(err.has_error()) << err.message();
+
+  // Same thing with a pattern in the output should fail.
+  TestParseInput input_bad(
+      "action(\"foo\") {\n"
+      "  script = \"//foo.py\"\n"
+      "  sources = [ \"//bar.txt\" ]\n"
+      "  outputs = [ \"//out/Debug/{{source_name_part}}.txt\" ]\n"
+      "}");
+  ASSERT_FALSE(input_bad.has_error());
+
+  // This should run fine.
+  input_bad.parsed()->Execute(setup.scope(), &err);
+  ASSERT_TRUE(err.has_error());
+}