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Refactor AsyncMock setup logic in create_autospec #81228

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tirkarthi opened this issue May 25, 2019 · 2 comments
Closed

Refactor AsyncMock setup logic in create_autospec #81228

tirkarthi opened this issue May 25, 2019 · 2 comments
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3.8 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@tirkarthi
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BPO 37047
Nosy @cjw296, @voidspace, @asvetlov, @1st1, @lisroach, @mariocj89, @tirkarthi
PRs
  • bpo-37047: Refactor AsyncMock setup logic for autospeccing #13574
  • Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
    closed_at = <Date 2019-05-27.12:56:57.361>
    created_at = <Date 2019-05-25.19:38:44.818>
    labels = ['3.8', 'type-bug', 'library']
    title = 'Refactor AsyncMock setup logic in create_autospec'
    updated_at = <Date 2019-05-27.12:56:57.360>
    user = 'https://github.com/tirkarthi'

    bugs.python.org fields:

    activity = <Date 2019-05-27.12:56:57.360>
    actor = 'yselivanov'
    assignee = 'none'
    closed = True
    closed_date = <Date 2019-05-27.12:56:57.361>
    closer = 'yselivanov'
    components = ['Library (Lib)']
    creation = <Date 2019-05-25.19:38:44.818>
    creator = 'xtreak'
    dependencies = []
    files = []
    hgrepos = []
    issue_num = 37047
    keywords = ['patch']
    message_count = 2.0
    messages = ['343504', '343620']
    nosy_count = 7.0
    nosy_names = ['cjw296', 'michael.foord', 'asvetlov', 'yselivanov', 'lisroach', 'mariocj89', 'xtreak']
    pr_nums = ['13574']
    priority = 'normal'
    resolution = 'fixed'
    stage = 'resolved'
    status = 'closed'
    superseder = None
    type = 'behavior'
    url = 'https://bugs.python.org/issue37047'
    versions = ['Python 3.8']

    @tirkarthi
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    • In create_autospec there is some logic to detect if the function is an async function this could be refactored out as a private function.

    • create_autospec has initialization code for async mock. For synchronous functions this is done with _setup_func and is called during setting signature. AsyncMock needs different setup logic code to setup the functions but the code can be refactored out of create_autospec into _setup_async_func.

    • In create_autospec awaited attribute is not set for AsyncMock during setup [0] and hence this causes AttributeError when the coroutine is awaited. awaited attribute can be also initialized.

    import asyncio
    from unittest.mock import create_autospec
    
    async def foo(): pass
    
    spec = create_autospec(foo)
    awaitable = spec()
    
    async def main(): await awaitable
    
    asyncio.run(main())
    Traceback (most recent call last):
      File "/tmp/spam.py", line 13, in <module>
        asyncio.run(main())
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/asyncio/runners.py", line 43, in run
        return loop.run_until_complete(main)
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/asyncio/base_events.py", line 614, in run_until_complete
        return future.result()
      File "/tmp/spam.py", line 11, in main
        await awaitable
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/mock.py", line 2045, in _mock_call
        return await proxy()
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/mock.py", line 2043, in proxy
        await self.awaited._notify()
      File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/mock.py", line 596, in __getattr__
        raise AttributeError("Mock object has no attribute %r" % name)
    AttributeError: Mock object has no attribute 'awaited'
    • In the setup logic to create attributes like assert_not_awaited uses the pattern setattr(mock, a, f) at [1] . But due to late binding 'a' in the function f has the last value of the loop 'assert_not_awaited' and hence calling other helpers also calls assert_not_awaited. This could be resolved by using a partial function that binds the attribute value early in the loop and respective function would be used in getattr.
    >>> spec.assert_awaited_once_with(1) # Due to late binding assert_not_awaited is always called
    TypeError: assert_not_awaited() takes 1 positional argument but 2 were given
    • assert_not_awaited has the error message indicating it should be awaited once [2] . This can be changed to indicate something like "Expected mock to not have been awaited".
    >>> spec.assert_not_awaited()
    AssertionError: Expected mock to have been awaited once. Awaited 1 times.
    • mock docs have list of magic methods implemented where __aenter__, __aexit__, __aiter__ and __anext__ could be documented with versionadded directive. [3]

    I have a PR with the above changes that I will post shortly for review.

    [0]

    mock._is_coroutine = asyncio.coroutines._is_coroutine

    [1]
    def f(*args, **kwargs):

    [2]
    msg = (f"Expected {self._mock_name or 'mock'} to have been awaited once."

    [3] https://docs.python.org/3.8/library/unittest.mock.html#mocking-magic-methods

    @tirkarthi tirkarthi added 3.8 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels May 25, 2019
    @1st1
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    1st1 commented May 27, 2019

    New changeset ff6b2e6 by Yury Selivanov (Xtreak) in branch 'master':
    bpo-37047: Refactor AsyncMock setup logic for autospeccing (GH-13574)
    ff6b2e6

    @1st1 1st1 closed this as completed May 27, 2019
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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    Labels
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