def test_metadata(self):
        """
        The log messages written by StdioOnnaStick have printed=1 keyword, and
        by default are not errors.
        """
        stdio = log.StdioOnnaStick()
        stdio.write("hello\n")
        self.assertFalse(self.resultLogs[0]['isError'])
        self.assertTrue(self.resultLogs[0]['printed'])

        The log messages written by StdioOnnaStick have printed=1 keyword, and
        by default are not errors.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_log.py