def METHOD_NAME(self):
    """
    Awaiting an already failed Deferred will raise the exception.
    """
    async def test():
        try:
            await fail(ValueError("Boom"))
        except ValueError as e:
            self.assertEqual(e.args, ("Boom",))
            return 1
        return 0
    res = self.successResultOf(Deferred.fromCoroutine(test()))
    self.assertEqual(res, 1)