def test_multipleAuthAdded(self):
        """
        Multiple C{--auth} command-line options will add all checkers specified
        to the list ofcheckers, and there should only be the specified auth
        checkers (no default checkers).
        """
        self.options.parseOptions(['--auth', 'file:' + self.filename,
                                   '--auth', 'memory:testuser:testpassword'])
        self.assertEqual(len(self.options['credCheckers']), 2)

        Multiple C{--auth} command-line options will add all checkers specified
        to the list ofcheckers, and there should only be the specified auth
        checkers (no default checkers).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_tap.py