gistfile1.py

    def testErrbackedDeferredFiresWithTheRightResult(self):
        """
        The pool must correctly pass the original deferred errback result
        through any callbacks it might have added.
        """
        expectedValue = Exception()
        pool = DeferredPool()
        d = Deferred()
        pool.add(d)
        pool.notifyWhenEmpty()
        d.errback(expectedValue)
        self.assertIdentical(d.result.value, expectedValue)
        self.assertFailure(d, Exception)