def test_start(self):
        """
        L{app.AppLogger.start} calls L{globalLogBeginner.addObserver}, and then
        writes some messages about twistd and the reactor.
        """
        logger = app.AppLogger({})
        observer = self._makeObserver()
        logger._getLogObserver = lambda: observer
        logger.start(Componentized())
        self._checkObserver(observer)

        L{app.AppLogger.start} calls L{globalLogBeginner.addObserver}, and then
        writes some messages about twistd and the reactor.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_twistd.py