Fix monkeypatch.setattr() teardown crash on failed setattr#14209
Open
worksbyfriday wants to merge 1 commit intopytest-dev:mainfrom
Open
Fix monkeypatch.setattr() teardown crash on failed setattr#14209worksbyfriday wants to merge 1 commit intopytest-dev:mainfrom
worksbyfriday wants to merge 1 commit intopytest-dev:mainfrom
Conversation
…v#14161) When setattr() fails (e.g. because the target is immutable like None), the undo stack already had the entry appended before the setattr call. This left a stale (target, name, NOTSET) entry that would crash during teardown with AttributeError trying to delattr on the target. Fix by moving the _setattr.append() after the setattr() call, so failed setattr operations don't pollute the undo stack. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
psf-chronographer
bot
added
the
bot:chronographer:provided
RonnyPfannschmidt
approved these changes
Feb 18, 2026
Member
RonnyPfannschmidt
left a comment
RonnyPfannschmidt
left a comment
There was a problem hiding this comment.
looks good, thanks
if you like you can use
with monkeypatch.context() as ctx:
with pytest.raises(...):
ctx.setattr(...)to pin down the monkey-patch used to something very constrained
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #14161.
When
monkeypatch.setattr(target, name, value, raising=False)is called on a target that doesn't support attribute setting (e.g.Noneor other immutable objects), the underlyingsetattr()raisesAttributeError. But the undo stack entry was appended before thesetattr()call, leaving a stale(target, name, NOTSET)entry. During teardown,undo()then triesdelattr(target, name), causing a secondAttributeErrorcrash.Fix: Move the
_setattr.append()call after thesetattr()call, so only successful attribute modifications get undo entries.