def test_unsupportedInterfaceError(self):
        """
        The C{--auth} command line raises an exception when it
        gets a checker we don't support.
        """
        options = OptionsSupportsNoInterfaces()
        authType = cred_anonymous.theAnonymousCheckerFactory.authType
        self.assertRaises(
            usage.UsageError,
            options.parseOptions, ['--auth', authType])

        The C{--auth} command line raises an exception when it
        gets a checker we don't support.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/cred/test/test_strcred.py