'When the process fails, the before-shutdown event is unregistered.'

def test_unregisters_killer_failure(self):

    reactor = ProcessCoreReactor()
    d = run(reactor, ['command', 'and', 'args'])
    [process] = reactor.processes
    process.processProtocol.processEnded(Failure(ProcessTerminated(1)))
    self.failureResultOf(d)
    self.assertEqual(reactor._triggers['shutdown'].before, [])
