'Just like testHandledTerminalFailure, only with a Deferred which fires
asynchronously with an error.'

def testHandledTerminalAsyncFailure(self):

    d = defer.Deferred()
    deferredGeneratorResultDeferred = self._genHandledTerminalAsyncFailure(d)
    d.errback(TerminalException('Handled    Terminal    Failure'))
    return deferredGeneratorResultDeferred.addCallback(self.assertEqual, None)
