Refs: https://github.com/Martiusweb/asynctest/issues/114

I was trying to mock a `asyncio.run(asyncio.gather())` call and I discovered that while it was working with `loop.run_until_complete` it wasn't with `asyncio.run`

Is there a reason for this difference of behaviour?

```
import asyncio
from unittest.mock import Mock


class AsyncMock(Mock):

    def __call__(self, *args, **kwargs):
        sup = super(AsyncMock, self)
        async def coro():
            return sup.__call__(*args, **kwargs)
        return coro()

    def __await__(self):
        return self().__await__()

mocked_function = AsyncMock()

asyncio.run(asyncio.gather(mocked_function()))
```

```
import asyncio
from unittest.mock import Mock


class AsyncMock(Mock):

    def __call__(self, *args, **kwargs):
        sup = super(AsyncMock, self)
        async def coro():
            return sup.__call__(*args, **kwargs)
        return coro()

    def __await__(self):
        return self().__await__()

mocked_function = AsyncMock()

loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.gather(mocked_function()))
```

asyncio.run() requires a coroutine, whereas gather() returns a subclass of asyncio.Future.
https://docs.python.org/dev/library/asyncio-task.html#asyncio.run

You can wrap gather() into a coroutine like that:
---
async def main():
    await asyncio.gather(mocked_function())

asyncio.run(main())
---

loop.run_until_complete() is different. It requires a "future", not a coroutine.
https://docs.python.org/dev/library/asyncio-eventloop.html#asyncio.loop.run_until_complete

gather() creates a future which is linked to the current event loop, whereas asyncio.run() creates a new event loop for the lifetime of run(). You should not pass a Future from an event loop to another event loop.

It's not a bug ;-)

Thank you for the clarification :)

nosy: + vstinner
messages: + msg337376

resolution: not a bug
stage: resolved