def test_logLevelValid(self):
        """
        L{TwistOptions.opt_log_level} sets the corresponding log level.
        """
        options = TwistOptions()
        options.opt_log_level("warn")

        self.assertIdentical(options["logLevel"], LogLevel.warn)

        L{TwistOptions.opt_log_level} sets the corresponding log level.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/twist/test/test_options.py