'Calling L{ClientService.stopService} on a stopped service
returns a L{Deferred} that has already fired with L{None}.'

def test_stopServiceOnStoppedService(self):

    clock = Clock()
    (_, service) = self.makeReconnector(fireImmediately=False, clock=clock)
    firstStopDeferred = service.stopService()
    secondStopDeferred = service.stopService()
    self.assertIsNone(self.successResultOf(firstStopDeferred))
    self.assertIsNone(self.successResultOf(secondStopDeferred))
