Add initial prototype for the GN meta-buildsystem.

tools/gn/string_utils_unittest.cc

Index: tools/gn/string_utils_unittest.cc
diff --git a/tools/gn/string_utils_unittest.cc b/tools/gn/string_utils_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..81181d27e67678e05ca6fece186647e306d1e6f1
--- /dev/null
+++ b/tools/gn/string_utils_unittest.cc
@@ -0,0 +1,71 @@
+// 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/err.h"
+#include "tools/gn/scope.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/string_utils.h"
+#include "tools/gn/token.h"
+#include "tools/gn/value.h"
+
+namespace {
+
+bool CheckExpansionCase(const char* input, const char* expected, bool success) {
+  Scope scope(static_cast<const Settings*>(NULL));
+  scope.SetValue("one", Value(NULL, 1), NULL);
+  scope.SetValue("onestring", Value(NULL, "one"), NULL);
+
+  // Construct the string token, which includes the quotes.
+  std::string literal_string;
+  literal_string.push_back('"');
+  literal_string.append(input);
+  literal_string.push_back('"');
+  Token literal(Location(), Token::STRING, literal_string);
+
+  Value result(NULL, Value::STRING);
+  Err err;
+  bool ret = ExpandStringLiteral(&scope, literal, &result, &err);
+
+  // Err and return value should agree.
+  EXPECT_NE(ret, err.has_error());
+
+  if (ret != success)
+    return false;
+
+  if (!success)
+    return true;  // Don't check result on failure.
+  return result.string_value() == expected;
+}
+
+}  // namespace
+
+TEST(StringUtils, ExpandStringLiteral) {
+  EXPECT_TRUE(CheckExpansionCase("", "", true));
+  EXPECT_TRUE(CheckExpansionCase("hello", "hello", true));
+  EXPECT_TRUE(CheckExpansionCase("hello #$one", "hello #1", true));
+  EXPECT_TRUE(CheckExpansionCase("hello #$one/two", "hello #1/two", true));
+  EXPECT_TRUE(CheckExpansionCase("hello #${one}", "hello #1", true));
+  EXPECT_TRUE(CheckExpansionCase("hello #${one}one", "hello #1one", true));
+  EXPECT_TRUE(CheckExpansionCase("hello #${one}$one", "hello #11", true));
+  EXPECT_TRUE(CheckExpansionCase("$onestring${one}$one", "one11", true));
+
+  // Errors
+  EXPECT_TRUE(CheckExpansionCase("hello #$", NULL, false));
+  EXPECT_TRUE(CheckExpansionCase("hello #$%", NULL, false));
+  EXPECT_TRUE(CheckExpansionCase("hello #${", NULL, false));
+  EXPECT_TRUE(CheckExpansionCase("hello #${}", NULL, false));
+  EXPECT_TRUE(CheckExpansionCase("hello #$nonexistant", NULL, false));
+  EXPECT_TRUE(CheckExpansionCase("hello #${unterminated", NULL, false));
+
+  // Unknown backslash values aren't special.
+  EXPECT_TRUE(CheckExpansionCase("\\", "\\", true));
+  EXPECT_TRUE(CheckExpansionCase("\\b", "\\b", true));
+
+  // Backslashes escape some special things. \"\$\\ -> "$\  Note that gtest
+  // doesn't like this escape sequence so we have to put it out-of-line.
+  const char* in = "\\\"\\$\\\\";
+  const char* out = "\"$\\";
+  EXPECT_TRUE(CheckExpansionCase(in, out, true));
+}