'Test that when a DelayedCall is cancelled it does not run.'

def test_cancelDelayedCall(self):

    called = []
    def function():
        called.append(None)
    call = reactor.callLater(0, function)
    call.cancel()
    d = Deferred()
    def check():
        try:
            self.assertEqual(called, [])
        except:
            d.errback()
        else:
            d.callback(None)
    reactor.callLater(0, reactor.callLater, 0, check)
    return d
