def test_invalidAuthError(self):
        """
        The C{--auth} command line raises an exception when it
        gets a parameter it doesn't understand.
        """
        options = DummyOptions()
        # If someone adds a 'ThisPluginDoesNotExist' then this unit
        # test should still run.
        invalidParameter = getInvalidAuthType()
        self.assertRaises(
            usage.UsageError,
            options.parseOptions, ['--auth', invalidParameter])
        self.assertRaises(
            usage.UsageError,
            options.parseOptions, ['--help-auth-type', invalidParameter])

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