Signature for unittest.mock.mock_open incomplete #15856
Description
After upgrading types-mock to 5.2, pyright is now reporting errors for the signature of mock_open.
My investigation indicates that this is due to #14063.
Reproducer on my local machine:
┬─[enno@framework-enno:/t/types-mock-issue]─[12:22:51]─[V:.venv]
╰─>$ cat test.py
# pyright: strict
from typing import TYPE_CHECKING
if TYPE_CHECKING:
from pytest_mock import MockerFixture
def test_example(mocker: "MockerFixture"):
mock_open = mocker.patch("builtins.open", mocker.mock_open())
pytest_mock was chosen as a reproducer because it was the easiest for me. I don't think it is at fault here because of the following call chain:
I am aware of the following comment, but having broken type annotations in the standard library seems a bit excessive to me: #14029 (comment)
Activity
srittau commented on Jun 2, 2026
Please note that this is a problem in the third-party stubs for mock, not the standard library, which has "fully" annotated (although probably incorrectly):
typeshed/stdlib/unittest/mock.pyi
Line 537 in 5f301d6
That said, incomplete stubs are expected in typeshed, and we don't keep issues about this open, although we value any contribution to complete our stubs.