New submission from Karthikeyan Singaravelan <tir.kar...@gmail.com>:
Since issue26467 implemented AsyncMock along with async dunder methods for
MagicMock it enables users to mock async for and async with statements.
Currently examples of how to use this is present only in tests and would be
good to add it to docs. There is a docs page for mock that contains similar
cookbook style examples [0] where I hope these can be added. I can raise a PR
with these examples if it's okay. Do you think it's worthy enough to add these
examples? Any additional examples you find around asyncio and mock that can be
documented ?
An example of mocking async for statement by setting return value for __aiter__
method :
# aiter_example.py
import asyncio
from unittest.mock import MagicMock
mock = MagicMock()
mock.__aiter__.return_value = range(3)
async def main():
print([i async for i in mock])
asyncio.run(main())
$ ./python.exe aiter_example.py
[0, 1, 2]
An example of mocking async with statement by implementing __aenter__ and
__aexit__ method. In this example __aenter__ and __aexit__ are not called.
__aenter__ and __aexit__ implementations are tested to have been called in the
test at [1]. These tests work since MagicMock is returned during attribute
access (mock_instance.entered) which is always True in boolean context under
assertTrue. I will raise a separate PR to discuss this since normally while
mocking __enter__ and __exit__ the class's __enter__ and __exit__ are not used
as a side_effect for the mock calls unless they are set explicitly.
# aenter_example.py
import asyncio
from unittest.mock import MagicMock
class WithAsyncContextManager:
async def __aenter__(self, *args, **kwargs):
return self
async def __aexit__(self, *args, **kwargs):
pass
instance = WithAsyncContextManager()
mock_instance = MagicMock(instance)
async def main():
async with mock_instance as result:
print("entered")
asyncio.run(main())
./python.exe aenter_example.py
entered
[0] https://docs.python.org/3/library/unittest.mock-examples.html
[1]
https://github.com/python/cpython/blob/47dd2f9fd86c32a79e77fef1fbb1ce25dc929de6/Lib/unittest/test/testmock/testasync.py#L306
----------
assignee: docs@python
components: Documentation
messages: 343536
nosy: asvetlov, cjw296, docs@python, lisroach, mariocj89, michael.foord,
xtreak, yselivanov
priority: normal
severity: normal
status: open
title: Add examples for mocking async for and async context manager in
unittest.mock docs
type: enhancement
versions: Python 3.8
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue37052>
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