Fix RuntimeWarning in unittest.mock asyncio example

[tirkarthi]

• This PR fixes the RuntimeWarning in inspect.isawaitable(mock()) where mock() was not awaited.
• Fix typo in asynctest project.

[tirkarthi]

cc: @lisroach I couldn't find a better way to suppress the RuntimeWarning than using the object in the example. Feel free to suggest if there is a better method.

Sample warning : https://travis-ci.org/python/cpython/jobs/534904298#L1553

[asvetlov]

thanks!

[asvetlov]

I removed automerge label.
Will apply it tomorrow if nobody will propose an alternative solution.

[tirkarthi]

@asvetlov There is one more https://travis-ci.org/python/cpython/jobs/534932562#L1564 . I am not sure why my local build and CI doesn't show all the warnings initially.

[tirkarthi]

I went ahead and removed the warning line in current CI and I get below one. For each line I remove, the subsequent line that accesses mock.await* attribute gets me this warning. Making it as a separate doctest with python -Wall -m doctest doesn't show any warning. I guess I must be missing something since subsequent lines keep raising RuntimeWarning.

<doctest default[3]>:1: RuntimeWarning: coroutine 'AsyncMockMixin._mock_call' was never awaited
  mock.await_args

[tirkarthi]

I have removed another call by guessing at 7ece18f and there is no RuntimeWarning now in CI. But removing it seems incorrect because as per the section it's there to illustrate that setting spec on Mock/MagicMock will return coroutine object on calling the object. Adding asyncio.main() to await it seems to clutter the simple example. Perhaps doctest can be converted to a codeblock with the repr of the object as comment on the same line to illustrate this. Suggestions welcome.

[eamanu]

LGTM

[lisroach]

Hmm weird, I hadn't seen these warnings when I ran locally. Thanks for digging into it @tirkarthi! I definitely wish we could avoid cluttering the simple examples. I'll try to take a look tonight but no solution off the top of my head.

[tirkarthi]

A simplified version of the changes. The builtins._ = None is just mock() with incorrect traceback I assume which is at the end of file

foo.rst

>>> import asyncio
>>> import inspect
>>> from unittest.mock import AsyncMock, MagicMock
>>> mock = AsyncMock()
>>> asyncio.iscoroutinefunction(mock)
True
>>> inspect.isawaitable(mock())
True
>>> async def async_func(): pass
...
>>> mock = MagicMock(async_func)
>>> mock   # doctest: +ELLIPSIS
<MagicMock spec='function' id='...'>
>>> mock()  # doctest: +ELLIPSIS
<coroutine object AsyncMockMixin._mock_call at ...>

./python.exe -X tracemalloc -Wall -m doctest foo.rst
<doctest foo.rst[5]>:1: RuntimeWarning: coroutine 'AsyncMockMixin._mock_call' was never awaited
  inspect.isawaitable(mock())
Object allocated at (most recent call last):
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/mock.py", lineno 992
    return _mock_self._mock_call(*args, **kwargs)
/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py:1485: RuntimeWarning: coroutine 'AsyncMockMixin._mock_call' was never awaited
  builtins._ = None
Object allocated at (most recent call last):
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/mock.py", lineno 992
    return _mock_self._mock_call(*args, **kwargs)

[asvetlov]

Dropping doctests for async mocks is another option.
asyncio is still not doctest-friendly.
Perhaps #13148 can change the situation a lot.

[tirkarthi]

Dropping doctest is a good idea. I have added # doctest: +SKIP to the statements that return coroutine objects not awaited. This fixes the warnings and also ensures that the examples are also concise. Thanks.

[asvetlov]

thanks!

[Carreau]

Perhaps #13148 can change the situation a lot.

Not quite sure I understand why. Do you mean you want >>> await coro in doctest ?

Another option is to set coroutine_wrapper (which is due for removal), track coroutine creations, and after each doctest check if the list of coro we have collected have been awaited at least once. If not raise an error, so now you can narrow down which doctest did forget to await coros instead of waiting for interpreter shutdown for the warning.

[asvetlov]

Yes, I mean after #13148 landing there is a possibility for extending doctest to support asyncio.
This requires some amount of work, sure. A good target for Python 3.9 :)