combine base_unittest.py modules from gm and tools

gm/rebaseline_server/imagepair_test.py

 #!/usr/bin/python
 
 """
 Copyright 2014 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
 Test imagepair.py
 """
 
 # System-level imports
 import shutil
 import tempfile
 import unittest
 
 # Local imports
 import imagediffdb
 import imagepair
 
 
 IMG_URL_BASE = ('http://chromium-skia-gm.commondatastorage.googleapis.com/'
                 'gm/bitmap-64bitMD5/')
 
 
 class ImagePairTest(unittest.TestCase):
 
   def setUp(self):
-    self._temp_dir = tempfile.mkdtemp()
+    self.temp_dir = tempfile.mkdtemp()
     self.maxDiff = None
 
   def tearDown(self):
-    shutil.rmtree(self._temp_dir)
+    shutil.rmtree(self.temp_dir)
 
   def shortDescription(self):
     """Tells unittest framework to not print docstrings for test cases."""
     return None
 
   def test_endToEnd(self):
     """Tests ImagePair, using a real ImageDiffDB to download real images.
 
     TODO(epoger): Either in addition to or instead of this end-to-end test,
     we should perform some tests using either:
@@ skipping 112 matching lines @@
                     'builder': 'MyBuilder',
                     'test': 'MyTest',
                 },
                 'imageAUrl': 'arcofzorro/16206093933823793653.png',
                 'imageBUrl': 'nonexistentDir/111111.png',
                 'isDifferent': True,
             },
         ],
     ]
 
-    db = imagediffdb.ImageDiffDB(self._temp_dir)
+    db = imagediffdb.ImageDiffDB(self.temp_dir)
     for selftest in selftests:
       image_pair = imagepair.ImagePair(
           image_diff_db=db,
           base_url=IMG_URL_BASE,
           imageA_relative_url=selftest[0],
           imageB_relative_url=selftest[1],
           expectations=selftest[2],
           extra_columns=selftest[3])
       self.assertEqual(image_pair.as_dict(), selftest[4])
 
 
 def main():
   suite = unittest.TestLoader().loadTestsFromTestCase(ImagePairTest)
   unittest.TextTestRunner(verbosity=2).run(suite)
 
 
 if __name__ == '__main__':
   main()