Show return type annotations in --fixtures and --fixtures-per-test

[IslamElsayed]

Closes #13676.

Fixtures with a return annotation now show it in --fixtures and --fixtures-per-test:

answer -> int -- test_x.py:4
    Answer to the Ultimate Question of Life, the Universe, and Everything.

This picks up where #13680 left off (thanks @kianelbo), following what was agreed there:

• On Python 3.14+ the annotation is read as a string with annotationlib.get_annotations(func, format=Format.STRING), as @The-Compiler suggested. Nothing is evaluated, which covers @RonnyPfannschmidt's point about unresolvable annotations: a name imported only under TYPE_CHECKING is shown, not raised.
• Before 3.14 it uses inspect.formatannotation, with no regex post-processing, per @nicoddemus. It passes base_module=func.__module__, so a class from the fixture's own module shows as Answer rather than test_x.Answer. String annotations (from __future__ import annotations) are shown as written.
• -> None is shown as None, and fixtures without a return annotation are unchanged.

Built-in fixtures now show their annotations too (tmp_path -> Generator[Path]), so the existing TestShowFixtures expectations are updated. The new tests use pytester modules without the __future__ import, so the object path is covered on older Pythons, plus one test for an unresolvable TYPE_CHECKING name with the import and one, run on 3.14+ only, without it. I ran the affected tests on 3.10, 3.13 and 3.14.

I left the display format as in the issue (name -> type -- path) and only touched --fixtures and --fixtures-per-test.

AI assistance (Claude) was used while preparing this; I've reviewed the change, understand it, and will handle the review myself.

[RonnyPfannschmidt]

🤖 Written by Claude Opus 5.5 via Claude Code for the pytest maintainers; I prompted it, it did the work, I read it.

Thanks, this follows the plan from #13680 well. Three changes before merge:

1. Yield fixtures: show the yielded type, not the wrapper. tmp_path -> Generator[Path] should read tmp_path -> Path. Strip Generator/Iterator/Iterable and their async variants to the first type argument, but only when the fixture function is actually a generator, so a plain fixture that returns an Iterator keeps its annotation. Please add tests for both cases.
2. Module prefixes: nested names such as Optional[test_x.Answer] before 3.14 are fine as they are. No need to strip them.
3. Odd fixture functions: if reading or formatting the annotation fails for any reason, don't crash or silently drop it. Print a short note under the fixture saying the return type can't be shown and where the fixture is defined. Please add a test for that path.

---

Generated by Claude Code

[IslamElsayed]

Thanks @RonnyPfannschmidt , all three are done:

1. Yield fixtures show the yielded type now (tmp_path -> Path). Generator/Iterator/Iterable and their async forms are unwrapped to the first argument only when the fixture function is a generator, so a plain fixture returning Iterator[int] keeps it. Covered with and without from __future__ import annotations, plus yield fixtures whose annotation isn't a wrapper (they keep it as written).
2. Module prefixes: left as they are.
3. Odd fixture functions: if reading or formatting the annotation fails, the fixture is still listed, with a note saying the return type can't be shown and where the fixture is defined. One catch: on 3.14 pytest's own collection reads the same string annotations (inspect.signature in getfuncargnames), so a fixture whose annotations can't be read already fails collection before --fixtures runs. The end-to-end test therefore runs below 3.14 only, and a unit test covers the helper on 3.14 as well.

Changes are in 21a6d40 and a48e007. The Read the Docs failure is a pluggy cross-reference warning (pluggy._compat.DistFacade) that also showed up on #15209, so it doesn't look related to this PR.