Since 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
I think this is a great addition! Ezio and I were chatting about trying to add an example where the child mocks are also AsyncMocks, since by default they will be MagicMocks. Adding him to nosy.
I will open a separate PR as discussed around mocking a class with an async method which is patched with AsyncMock. Meanwhile a method that returns a coroutine is patched with a MagicMock and needs to be explicitly mocked with an AsyncMock as new in the patch call. The original example in Zulip is as below showing the difference. from unittest.mock import AsyncMock, patch import asyncio async def foo(): pass async def post(url): pass class Response: async def json(self): pass def sync_json(self): return foo() # Returns a coroutine which should be awaited to get the result async def main(): # post function is an async function and hence AsyncMock is returned. with patch(f"{__name__}.post", return_value={'a': 1}) as m: print(await post("http://example.com")) # The json method call is a coroutine whose return_value is set with the dictionary # json is an async function and hence during patching here m is an AsyncMock response = Response() with patch.object(response, 'json', return_value={'a': 1}): print(await response.json()) # sync_json returns a coroutine and not an async def itself. So it's mocked as MagicMock # by patch.object and we need to pass an explicit callable as AsyncMock to make sure it's # awaitable response = Response() with patch.object(response, 'sync_json', AsyncMock(return_value={'a': 1})): print(await response.sync_json()) asyncio.run(main())
