Make running gn format unittests from anywhere work

tools/gn/command_format_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 "base/files/file_util.h"
+#include "base/path_service.h"
 #include "base/strings/string_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/setup.h"
 
 namespace commands {
 bool FormatFileToString(Setup* setup,
                         const SourceFile& file,
                         bool dump_tree,
                         std::string* output);
 }  // namespace commands
 
-#define FORMAT_TEST(n)                                                 \
-  TEST(Format, n) {                                                    \
-    ::Setup setup;                                                     \
-    std::string out;                                                   \
-    std::string expected;                                              \
-    EXPECT_TRUE(commands::FormatFileToString(                          \
-        &setup,                                                        \
-        SourceFile("//tools/gn/format_test_data/" #n ".gn"),           \
-        false,                                                         \
-        &out));                                                        \
-    ASSERT_TRUE(base::ReadFileToString(                                \
-        base::FilePath(FILE_PATH_LITERAL("tools/gn/format_test_data/") \
-                           FILE_PATH_LITERAL(#n)                       \
-                               FILE_PATH_LITERAL(".golden")),          \
-        &expected));                                                   \
-    EXPECT_EQ(expected, out);                                          \
+#define FORMAT_TEST(n)                                                      \
+  TEST(Format, n) {                                                         \
+    ::Setup setup;                                                          \
+    std::string out;                                                        \
+    std::string expected;                                                   \
+    base::FilePath exe;                                                     \
+    PathService::Get(base::FILE_EXE, &exe);                                 \

[Dirk Pranke, 2014/12/19 18:24:39]

Can you use PathService::Get(base::DIR_SOURCE_ROOT) here instead? I think that's
the normally recommended mechanism for finding paths for test data.

[tfarina, 2014/12/19 18:29:04]

+1 for that. I found DIR_SOURCE_ROOT easier to understand.

[scottmg, 2014/12/19 18:31:45]

Ah, indeed. Done.

(Sadly, it's doing the same thing, so is broken in the same way. But at least
it's broken the same way everywhere this way.)

+    base::FilePath src_dir = exe.DirName().DirName().DirName();             \
+    base::SetCurrentDirectory(src_dir);                                     \
+    EXPECT_TRUE(commands::FormatFileToString(                               \
+        &setup, SourceFile("//tools/gn/format_test_data/" #n ".gn"), false, \
+        &out));                                                             \
+    ASSERT_TRUE(base::ReadFileToString(                                     \
+        base::FilePath(FILE_PATH_LITERAL("tools/gn/format_test_data/")      \
+                           FILE_PATH_LITERAL(#n)                            \
+                               FILE_PATH_LITERAL(".golden")),               \
+        &expected));                                                        \
+    EXPECT_EQ(expected, out);                                               \
   }
 
 // These are expanded out this way rather than a runtime loop so that
 // --gtest_filter works as expected for individual test running.
 FORMAT_TEST(001)
 FORMAT_TEST(002)
 FORMAT_TEST(003)
 FORMAT_TEST(004)
 FORMAT_TEST(005)
 FORMAT_TEST(006)
@@ skipping 46 matching lines @@
 FORMAT_TEST(052)
 FORMAT_TEST(053)
 FORMAT_TEST(054)
 FORMAT_TEST(055)
 FORMAT_TEST(056)
 FORMAT_TEST(057)
 FORMAT_TEST(058)
 FORMAT_TEST(059)
 FORMAT_TEST(060)
 FORMAT_TEST(061)