python / python/cpython

Might mock.MagicMock be given a type parameter?

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#117,222 2 comments 1 reaction 0 assignees View on GitHub

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type-feature
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Python
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Description

Feature or enhancement

Proposal:

In the case of

class MyClass:
  def method_that_exists_on_my_class(self):
    pass

my_mock_thing = mock.create_autospec(MyClass)
my_mock_thing.method_that_exists_on_my_class()
my_mock_thing.method_that_does_not_exist_on_my_class()
my_mock_thing.method_that_exists_on_my_class.assert_called_once()
my_mock_thing.method_that_does_not_exist_on_my_class.assert_called_once()

it would be nice if the type of my_mock_thing were mock.MagicMock[MyClass] (instead of "raw" mock.MagicMock) so that type-checkers could alert me that my call to my_mock_thing.method_that_does_not_exist_on_my_class is a flaw in my test.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

(I looked around among both open and closed issues and didn't see anything on this topic; apologies if I overlooked an already-ongoing discussion...)

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Research direction

The proposal centers on mock.MagicMock and mock.create_autospec; start by locating those entry points and reviewing how mocks are currently typed. Then identify the relevant tests for autospec attribute access. Done means type checkers can flag nonexistent methods on an autospecced mock while preserving valid method access.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
testing-qa
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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