def test_authAdded(self):
        """
        The C{--auth} command-line option will add a checker to the list of
        checkers
        """
        numCheckers = len(self.options['credCheckers'])
        self.options.parseOptions(['--auth', 'file:' + self.filename])
        self.assertEqual(len(self.options['credCheckers']), numCheckers + 1)

        The C{--auth} command-line option will add a checker to the list of
        checkers
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_ftp_options.py