Notify ThreadingMock waiters before running side effects #159344

A ThreadingMock call is recorded even when its side effect raises, but the wait APIs still time out because their events are only set after successful completion of the side effect. The same ordering prevents a side effect from waiting on its own recorded call.

Reproducer, run with the interpreter built from the CPython checkout:

from unittest.mock import ThreadingMock

mock = ThreadingMock(side_effect=ValueError, timeout=0)
try:
    mock(1, key=2)
except ValueError:
    pass
mock.assert_called_once_with(1, key=2)
mock.wait_until_called()
mock.wait_until_any_call_with(1, key=2)

Expected: Both waits recognize the recorded call.

Observed: wait_until_called() raises AssertionError indicating the mock was not called before the timeout.

Environment: CPython main, Windows debug build.

Linked PRs

• gh-159344: Notify ThreadingMock waiters before running side effects #159345