mock.Mock() acts like a Future

[popravich]

Since this changes 32edb29d5b0524e0da2400908093de5911f117f4 unittest.mock.Mock being detected as asyncio.Future. asyncio.futures.isfuture checks for private attribute _asyncio_future_blocking to be not None and Mock() (without specs) returns new mock as this attribute.

The use case is here aio-libs/aioredis#161 — basically, function wrapped with asyncio.coroutine and set as Mock's method side_effect started to raise TypeError.

[gvanrossum]

Is there something you want us to do?

--Guido (mobile)

[1st1]

We can probably check obj.__class__ for _asyncio_future_blocking attribute.

[popravich]

Is there something you want us to do?

Yeah, it was more like FYI. Maybe a little bit stricter check would be better. Some use cases like implementing some kind of RPC with dynamic methods resolution might hit this case

[gvanrossum]

Can someone please translate the original post into an actionable issue for me? I do not understand what the OP is asking.

[1st1]

@gvanrossum Please see https://github.com/python/asyncio/pull/455.

[gvanrossum]

I'm not at all clear that a Mock should not be considered a Future. The clarification "Some use cases like implementing some kind of RPC with dynamic methods resolution" sounds awefully vague. Maybe there are just as many use cases that would break with this change?

[1st1]

Maybe there are just as many use cases that would break with this change?

isinstance(unittest.mock.Mock(), asyncio.Future) returns False. If we want to promote to use isfuture instead of isinstance, we should fix it.

[gvanrossum]

isinstance(unittest.mock.Mock(), asyncio.Future) returns False. If we want to promote to use isfuture instead of isinstance, we should fix it.

OK, that makes sense.

[gvanrossum]

Fixed by 26d01d796dccb365d3d6c00f8e35fe0d431b5abf (#455).

[popravich]

isinstance(unittest.mock.Mock(), asyncio.Future) returns False

isinstance(unittest.mock.Mock(asyncio.Future), asyncio.Future) will return True. But isfuture(unittest.mock.Mock(asyncio.Future)) will return False. Is that ok?

[1st1]

Oh. Let me see how Mocks work.

[1st1]

But isfuture(unittest.mock.Mock(asyncio.Future)) will return False. Is that ok?

Fixed.