def test_timeFormat(self):
        """
        Returned L{FileLogObserver} has the correct outFile.
        """
        with StringIO() as fileHandle:
            observer = textFileLogObserver(fileHandle, timeFormat=u"%f")
            observer(dict(log_format=u"XYZZY", log_time=112345.6))
            self.assertEqual(fileHandle.getvalue(), u"600000 [-#-] XYZZY\n")

        Returned L{FileLogObserver} has the correct outFile.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/logger/test/test_file.py