Create a new depot_tools_testing_lib to move utility modules there

tests/presubmit_unittest.py

 #!/usr/bin/env python
 # Copyright (c) 2011 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.
 
 """Unit tests for presubmit_support.py and presubmit_canned_checks.py."""
 
 # pylint: disable=E1101,E1103
 
 import logging
 import os
 import StringIO
 import sys
 import time
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
-from super_mox import mox, SuperMoxTestBase
+from testing_support.super_mox import mox, SuperMoxTestBase
 
 import owners
 import presubmit_support as presubmit
 import rietveld
 
 # Shortcut.
 presubmit_canned_checks = presubmit.presubmit_canned_checks
 
 
 class PresubmitTestsBase(SuperMoxTestBase):
@@ skipping 2204 matching lines @@
     self.assertEqual(1, len(results))
     # pylint: disable=W0212
     self.assertEqual(
         'Found line ending with white spaces in:', results[0]._message)
     self.checkstdout('')
 
 
 if __name__ == '__main__':
   import unittest
   unittest.main()