def test_untilFailureSuite(self):
        """
        The C{until-failure} configuration uses the L{TestSuite} to keep
        instances alive across runs.
        """
        self.config['until-failure'] = True
        loader = trial._getLoader(self.config)
        self.assertEqual(loader.suiteFactory, TestSuite)

        The C{until-failure} configuration uses the L{TestSuite} to keep
        instances alive across runs.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_script.py