rebaseline_server: constrain setADir/setBDir to consistently refer to single directories, not lists

gm/rebaseline_server/compare_rendered_pictures_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 compare_rendered_pictures.py
 
@@ skipping 38 matching lines @@
             'only-in-before.skp': 128,
         })
     self._generate_skps_and_run_render_pictures(
         subdir=setB_subdir, skpdict={
             'changed.skp': 201,
             'unchanged.skp': 100,
             'only-in-after.skp': 128,
         })
 
     results_obj = compare_rendered_pictures.RenderedPicturesComparisons(
-        setA_dirs=[os.path.join(self.temp_dir, setA_subdir)],
-        setB_dirs=[os.path.join(self.temp_dir, setB_subdir)],
+        setA_dir=os.path.join(self.temp_dir, setA_subdir),
+        setB_dir=os.path.join(self.temp_dir, setB_subdir),
         setA_section=gm_json.JSONKEY_ACTUALRESULTS,
         setB_section=gm_json.JSONKEY_ACTUALRESULTS,
         image_diff_db=imagediffdb.ImageDiffDB(self.temp_dir),
         image_base_gs_url='gs://fakebucket/fake/path',
         diff_base_url='/static/generated-images')
     results_obj.get_timestamp = mock_get_timestamp
 
     # Overwrite elements within the results that change from one test run
     # to the next.
     # pylint: disable=W0212
     results_obj._setA_descriptions[results.KEY__SET_DESCRIPTIONS__DIR] = [
         'before-patch-fake-dir']
     results_obj._setB_descriptions[results.KEY__SET_DESCRIPTIONS__DIR] = [
         'after-patch-fake-dir']
 
     gm_json.WriteToFile(
         results_obj.get_packaged_results_of_type(
             results.KEY__HEADER__RESULTS_ALL),
         os.path.join(self.output_dir_actual, 'compare_rendered_pictures.json'))
 
   def test_repo_url(self):
     """Use repo: URL to specify summary files."""
     base_repo_url = 'repo:gm/rebaseline_server/testdata/inputs/skp-summaries'
     results_obj = compare_rendered_pictures.RenderedPicturesComparisons(
-        setA_dirs=[posixpath.join(base_repo_url, 'expectations')],
-        setB_dirs=[posixpath.join(base_repo_url, 'actuals')],
+        setA_dir=posixpath.join(base_repo_url, 'expectations'),
+        setB_dir=posixpath.join(base_repo_url, 'actuals'),
         setA_section=gm_json.JSONKEY_EXPECTEDRESULTS,
         setB_section=gm_json.JSONKEY_ACTUALRESULTS,
         image_diff_db=imagediffdb.ImageDiffDB(self.temp_dir),
         image_base_gs_url='gs://fakebucket/fake/path',
         diff_base_url='/static/generated-images')
     results_obj.get_timestamp = mock_get_timestamp
 
     # Overwrite elements within the results that change from one test run
     # to the next.
     # pylint: disable=W0212
@@ skipping 58 matching lines @@
   """Mock version of BaseComparisons.get_timestamp() for testing."""
   return 12345678
 
 
 def main():
   base_unittest.main(CompareRenderedPicturesTest)
 
 
 if __name__ == '__main__':
   main()