Refactor `pytest_load_initial_conftests()` to split
the fork-spawn × capture-mode check into two policies:
- CI (`CI` env-var set): `pytest.exit(rc=2)` on
mismatch — forces every matrix-row to declare
`--capture=sys` explicitly.
- local: `warnings.warn()` + continue — lets devs
experiment with `--capture=fd` to validate fixes.
Deats,
- drop `_cap_fd_set` global; add
`_CAPSYS_REQUIRED_SPAWNERS` frozenset for the
spawner-name lookup
- move inline comment wall → proper docstring w/
Background, Trade-off, Validation-policy sections
- `maybe_xfail_for_spawner()` now takes
`request: pytest.FixtureRequest` and reads
`request.config.option.capture` instead of the
`_cap_sys_passed_as_flag` global
- recognize `tee-sys` as fork-safe (only `fd`-level
capture deadlocks)
- `set_fork_aware_capture()` returns the actual
capture mode str from config, not a hardcoded
`'sys'`
- lift `import warnings` to module level (was duped
inside `pytest_configure`)
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
(cherry picked from commit 255c9c3a7c)
Gud Boi
42a3ea2cf9