Add script tests for `gn check`, `gyp_flag_compare` to GN bot configs.

testing/scripts/gyp_flag_compare.py

Index: testing/scripts/gyp_flag_compare.py
diff --git a/testing/scripts/gyp_flag_compare.py b/testing/scripts/gyp_flag_compare.py
new file mode 100755
index 0000000000000000000000000000000000000000..2673c83ea723cd3f0b748b6d66cbd8ae02cec019
--- /dev/null
+++ b/testing/scripts/gyp_flag_compare.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+# Copyright 2015 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.
+
+"""Wrap //tools/gn/bin/gyp_flag_compare.py for the bots.
+
+This script wraps the GN test script in the facade needed for the
+'ScriptTest' step class of the chromium recipe_module
+(see scripts/slave/recipe_modules/chromium/steps.py in the build repo.
+
+The script takes N arguments, for the N targets to compare flags for.
+"""
+
+import json
+import os
+import sys
+
+
+import common
+
+
+def main_run(args):
+  rc = common.run_command([sys.executable,
+                           os.path.join(common.SRC_DIR,
+                                        'tools', 'gn', 'bin',
+                                        'gyp_flag_compare.py')] + args.args)

[Dirk Pranke, 2015/05/15 01:00:54]

gyp_flag_compare.py takes a list of build targets to look at. 

It would be nice if I could get main_compile_targets() to echo the same list of
build targets back, so that we could be sure that we were compiling them, but
from what i can tell, main_compile_targets doesn't actually get the list of args
passed to it? Am I wrong?

[Paweł Hajdan Jr., 2015/05/15 10:14:07]

FWIW I don't see any args being passed to this script in this CL.
Yeah, I think it isn't passed currently and we'd need to change ScriptTest for
that. Feel free to make such a change (it seems non-trivial though).

[Dirk Pranke, 2015/05/15 15:09:40]

Yeah, I didn't add the step at all to the json file, apparently.
It looked a bit difficult to me, too. I'll think about it some more.

+
+  json.dump({
+      'valid': True,
+      'failures': [],

[Paweł Hajdan Jr., 2015/05/15 10:14:07]

Do you intend this to always pass? If there are any failures they should be
added to this list.

[Dirk Pranke, 2015/05/15 15:09:40]

same answer as the other one. eventually we might be able to do something
smarter but I don't want to bother with it yet.

+  }, args.output)
+
+  return rc
+
+
+def main_compile_targets(args):
+  json.dump([], args.output)
+
+
+if __name__ == '__main__':
+  funcs = {
+    'run': main_run,
+    'compile_targets': main_compile_targets,
+  }
+  sys.exit(common.run_script(sys.argv[1:], funcs))