Description

Daverball

opened on Mar 10, 2026

Issue body actions

Bug report

Bug description:

from typing import TYPE_CHECKING
from unittest.mock import create_autospec

if TYPE_CHECKING:
    from foo import Foo

def bar(x: Foo) -> None:
    pass

create_autospec(bar)

This will result in NameError: name 'Foo' is not defined because _get_signature_object in unittest.mock calls inspect.signature without explicitly passing annotation_format, so it defaults to Format.VALUE.

Since create_autospec really shouldn't care whether or not the annotations can be evaluated at runtime on the given object, I would suggest switching over to Format.FORWARDREF or Format.STRING, so autospeccing continues to work in Python 3.14+ for people that used to rely on from __future__ import annotations and now want to switch to PEP 649 semantics, without needing to change their code.

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-145754: Update signature retrieval in unittest.mock to use forwardref annotation format #145756
• [3.14] gh-145754: Update signature retrieval in unittest.mock to use forwardref annotation format (GH-145756) #146191

Reacted by Matthieu Rigal

Activity

1. Daverball

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Mar 10, 2026
2. mschoettle

   marked unittest.mock requests VALUE annotation format when calling inspect.signature #145755 as a duplicate of this issue on Mar 10, 2026
3. johnslavik

   added

   topic-typing

   3.14bugs and security fixesbugs and security fixes

   3.15bugs and security fixesbugs and security fixes

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   and removed

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   topic-typing

   on Mar 10, 2026
4. JelleZijlstra

   added a commit that references this issue on Mar 20, 2026

   gh-145754: Update signature retrieval in unittest.mock to use forward…

   d357a7d
5. JelleZijlstra

   closed this as completedin #145756on Mar 20, 2026
6. miss-islington

   added a commit that references this issue on Mar 20, 2026

   pythongh-145754: Update signature retrieval in unittest.mock to use f…

   186b50d
7. JelleZijlstra

   added a commit that references this issue on Mar 20, 2026

   [3.14] gh-145754: Update signature retrieval in unittest.mock to use …

   7ba9580
8. CuriousLearner

   added a commit that references this issue on Mar 22, 2026

   Merge remote-tracking branch 'upstream/main' into fix-pythongh-138577

   2691ad9
9. ljfp

   added a commit that references this issue on Apr 25, 2026

   pythongh-145754: Update signature retrieval in unittest.mock to use f…

   ec9558a
10. akhmialeuski

    added a commit that references this issue on Oct 18, 2026

    refactor(tests): remove the leftovers of the in-memory adapter from t…

    d7002c0

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