Create a new depot_tools_testing_lib to move utility modules there

tests/rietveld_test.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 rietveld.py."""
 
 import logging
 import os
 import sys
 import unittest
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
+from testing_support.patches_data import GIT, RAW
+
 import patch
 import rietveld
-from tests.patches_data import GIT, RAW
 
 
 def _api(files):
   """Mock a rietveld api request."""
   return rietveld.json.dumps({'files': files})
 
 
 def _file(
     status, is_binary=False, num_chunks=1, chunk_id=789, property_changes=''):
   """Mock a file in a rietveld api request."""
@@ skipping 314 matching lines @@
         {'foo': 'prout'},
     ]
     for i in self.rietveld.search(base='base'):
       self.assertEquals(expected.pop(0), i)
     self.assertEquals([], expected)
 
 
 if __name__ == '__main__':
   logging.basicConfig(level=logging.ERROR)
   unittest.main()