Prepare python code for reftests.

sky/tools/webkitpy/layout_tests/controllers/test_result_writer_unittest.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 36 matching lines @@
         write_test_result(host.filesystem, port, '/tmp', 'foo.html', actual_output, expected_output, failures)
         return host.filesystem.written_files
 
     def test_success(self):
         # Nothing is written when the test passes.
         written_files = self.run_test(failures=[])
         self.assertEqual(written_files, {})
 
     def test_reference_exists(self):
         failure = test_failures.FailureReftestMismatch()
-        failure.reference_filename = '/src/exists-expected.html'
-        files = {'/src/exists-expected.html': 'yup'}
+        failure.reference_filename = '/src/exists-expected.sky'
+        files = {'/src/exists-expected.sky': 'yup'}
         written_files = self.run_test(failures=[failure], files=files)
-        self.assertEqual(written_files, {'/tmp/exists-expected.html': 'yup'})
+        self.assertEqual(written_files, {'/tmp/exists-expected.sky': 'yup'})
 
         failure = test_failures.FailureReftestMismatchDidNotOccur()
-        failure.reference_filename = '/src/exists-expected-mismatch.html'
-        files = {'/src/exists-expected-mismatch.html': 'yup'}
+        failure.reference_filename = '/src/exists-expected-mismatch.sky'
+        files = {'/src/exists-expected-mismatch.sky': 'yup'}
         written_files = self.run_test(failures=[failure], files=files)
-        self.assertEqual(written_files, {'/tmp/exists-expected-mismatch.html': 'yup'})
+        self.assertEqual(written_files, {'/tmp/exists-expected-mismatch.sky': 'yup'})
 
     def test_reference_is_missing(self):
         failure = test_failures.FailureReftestMismatch()
         failure.reference_filename = 'notfound.html'
         written_files = self.run_test(failures=[failure], files={})
         self.assertEqual(written_files, {})
 
         failure = test_failures.FailureReftestMismatchDidNotOccur()
         failure.reference_filename = 'notfound.html'
         written_files = self.run_test(failures=[failure], files={})
         self.assertEqual(written_files, {})