def test_callLaterUsesReactorSecondsInDelayedCall(self):
        """
        L{reactor.callLater<twisted.internet.interfaces.IReactorTime.callLater>}
        should use the reactor's seconds factory
        to produce the time at which the DelayedCall will be called.
        """
        oseconds = reactor.seconds
        reactor.seconds = lambda: 100
        try:
            call = reactor.callLater(5, lambda: None)
            self.assertEqual(call.getTime(), 105)
        finally:
            reactor.seconds = oseconds
        call.cancel()

        L{reactor.callLater<twisted.internet.interfaces.IReactorTime.callLater>}
        should use the reactor's seconds factory
        to produce the time at which the DelayedCall will be called.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_internet.py