Refactor GN source expansions.

tools/gn/substitution_pattern_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/err.h"
+#include "tools/gn/substitution_pattern.h"
+
+TEST(SubstitutionPattern, ParseLiteral) {
+  SubstitutionPattern pattern;
+  Err err;
+  EXPECT_TRUE(pattern.Parse("This is a literal", NULL, &err));
+  EXPECT_FALSE(err.has_error());
+  ASSERT_EQ(1u, pattern.ranges().size());
+  EXPECT_EQ(SUBSTITUTION_LITERAL, pattern.ranges()[0].type);
+  EXPECT_EQ("This is a literal", pattern.ranges()[0].literal);
+}
+
+TEST(SubstitutionPatterm, ParseComplex) {
+  SubstitutionPattern pattern;
+  Err err;
+  EXPECT_TRUE(pattern.Parse(
+      "AA{{source}}{{source_name_part}}BB{{source_file_part}}", NULL, &err));
+  EXPECT_FALSE(err.has_error());
+  ASSERT_EQ(5u, pattern.ranges().size());
+
+  EXPECT_EQ(SUBSTITUTION_LITERAL, pattern.ranges()[0].type);
+  EXPECT_EQ("AA", pattern.ranges()[0].literal);
+  EXPECT_EQ(SUBSTITUTION_SOURCE, pattern.ranges()[1].type);
+  EXPECT_EQ(SUBSTITUTION_SOURCE_NAME_PART, pattern.ranges()[2].type);
+  EXPECT_EQ(SUBSTITUTION_LITERAL, pattern.ranges()[3].type);
+  EXPECT_EQ("BB", pattern.ranges()[3].literal);
+  EXPECT_EQ(SUBSTITUTION_SOURCE_FILE_PART, pattern.ranges()[4].type);
+}
+
+TEST(SubstitutionPattern, ParseErrors) {
+  SubstitutionPattern pattern;
+  Err err;
+  EXPECT_FALSE(pattern.Parse("AA{{source", NULL, &err));
+  EXPECT_TRUE(err.has_error());
+
+  err = Err();
+  EXPECT_FALSE(pattern.Parse("{{source_of_evil}}", NULL, &err));
+  EXPECT_TRUE(err.has_error());
+
+  err = Err();
+  EXPECT_FALSE(pattern.Parse("{{source{{source}}", NULL, &err));
+  EXPECT_TRUE(err.has_error());
+}