def test_singleString(self):
        """
        Test simple output, and default log level.
        """
        self.lp.msg("Hello, world.")
        self.assertIn(b"Hello, world.", self.out.getvalue())
        self.assertIn(b"INFO", self.out.getvalue())

        Test simple output, and default log level.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_log.py