Fix fixture discovery to use definition order instead of alphabetical#14169
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veeceey wants to merge 4 commits intopytest-dev:mainfrom
Open
Fix fixture discovery to use definition order instead of alphabetical#14169veeceey wants to merge 4 commits intopytest-dev:mainfrom
veeceey wants to merge 4 commits intopytest-dev:mainfrom
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Fixtures are now discovered in their definition order (as they appear in source code) rather than alphabetical order. This change resolves issues where fixtures with the same name at different scopes would be processed in unexpected order due to dir() sorting. The fix changes parsefactories() to use __dict__ iteration (which preserves insertion order in Python 3.7+) instead of dir() which sorts. This makes fixture behavior predictable based on source code order. Fixes pytest-dev#11281 Related to pytest-dev#12952
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The previous implementation only looked at holderobj.__dict__ which is empty for new instances (e.g. unittest TestCase instances passed from unittest.py). This caused autouse fixtures defined on the class to not be discovered. Now properly handle three cases: - Modules: use module.__dict__ directly - Classes: walk __mro__ to get class and base class attributes - Instances: walk type(instance).__mro__ for class hierarchy Also add assert isinstance(holderobj, type) to satisfy mypy since safe_isclass() doesn't use TypeGuard.
- Add explicit type annotation `list[Mapping[str, Any]]` for dicts variable to fix mypy error about MappingProxyType vs dict mismatch (cls.__dict__ returns MappingProxyType for classes) - Fix test_autouse_fixtures_definition_order_preserved to use distinct fixture names and correct expectations (module + class fixtures both run, not just module)
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Summary
Fixes #11281
This PR changes fixture discovery to preserve definition order instead of using alphabetical sorting from
dir().Problem
Previously,
parsefactories()useddir()to iterate over object attributes, which sorts names alphabetically. This caused unexpected behavior when fixtures with the same name were defined at different scopes (e.g., module vs class level), because the order of discovery depended on alphabetical sorting rather than source code order.Solution
Changed
parsefactories()to use__dict__iteration (similar to howPyCollector.collect()works), which preserves insertion/definition order in Python 3.7+. This ensures fixtures are processed in the order they appear in source code, making behavior predictable and intuitive.Changes
FixtureManager.parsefactories()to iterate__dict__instead ofdir()PyCollector)Test plan