def test_cancelDeferredListWithFireOnOneErrbackAllDeferredsCallback(self):
        """
        When cancelling an unfired L{defer.DeferredList} with the flag
        C{fireOnOneErrback} set, if all the L{defer.Deferred} callbacks
        in its canceller, the L{defer.DeferredList} will callback with a
        C{list} of (success, result) C{tuple}s.
        """
        deferredOne = defer.Deferred(fakeCallbackCanceller)
        deferredTwo = defer.Deferred(fakeCallbackCanceller)
        deferredList = defer.DeferredList([deferredOne, deferredTwo],
                                          fireOnOneErrback=True)
        deferredList.cancel()
        result = self.successResultOf(deferredList)
        self.assertTrue(result[0][0])
        self.assertEqual(result[0][1], "Callback Result")
        self.assertTrue(result[1][0])
        self.assertEqual(result[1][1], "Callback Result")

        When cancelling an unfired L{defer.DeferredList} with the flag
        C{fireOnOneErrback} set, if all the L{defer.Deferred} callbacks
        in its canceller, the L{defer.DeferredList} will callback with a
        C{list} of (success, result) C{tuple}s.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_defer.py