gh-153888: Resolve lazy imports before using them as a mock spec - #157768
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unittest.mock.patch() reads the attribute it replaces out of target.__dict__, which for an unresolved lazy import holds a types.LazyImportType placeholder. spec=True, spec_set=True and autospec=True then specced the placeholder, so patching a function produced a NonCallableMagicMock. Reimplementation of python#153977, open since July 2026: - Resolve in _patch.__enter__(), and only when the spec is taken from the original, rather than unconditionally in get_original(). Resolving on every patch() breaks patch("mod.dep", new=...) for a lazy import of a module that is not installed. - Test spec and spec_set as well as autospec, as asked for in review. - Build the lazy binding in the test instead of importing json lazily at module level: "lazy from" binds eagerly when the module is already imported, so that test passed without the fix too. Reported as pythongh-153888.
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cc @encukou |
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This looks good to me -- though I'm not an expert on lazy modules or mock. It is a behaviour change though. Is it possible that someone would mock out a lazy import because it's not importable in the test scenario? @hugovk, does this fit in 3.15? |
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Yes, this can go into 3.15.0. |
encukou
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needs backport to 3.15
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Thanks @brittanyrey for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15. |
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GH-158396 is a backport of this pull request to the 3.15 branch. |
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unittest.mock.patch()reads the attribute it replaces out oftarget.__dict__, which for an unresolved lazy import holds atypes.LazyImportType placeholder.spec=True,spec_set=Trueandautospec=Truethen specced the placeholder, so patching a function produced aNonCallableMagicMock.Reimplementation of #153977, open since July 2026 + some additional tests and one extra check.
_patch.__enter__(), and only when the spec is taken from the original, rather than unconditionally inget_original(). Resolving on everypatch()breakspatch("mod.dep", new=...)for a lazy import of a module that is not installed.autospecdoesn't work with lazy-imported symbols #153888