def test_delayedCall(self):
        """
        If there is a delayed call, C{doIteration} is called with a timeout
        which is the difference between the current time and the time at
        which that call is to run.
        """
        reactor = TimeoutReportReactor()
        reactor.callLater(100, lambda: None)
        timeout = self._checkIterationTimeout(reactor)
        self.assertEqual(timeout, 100)

        If there is a delayed call, C{doIteration} is called with a timeout
        which is the difference between the current time and the time at
        which that call is to run.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_posixbase.py