Remove deprecated scope keyword argument from asyncio marker

[mokashang]

Fixes #1475.

What changed

The scope keyword argument to @pytest.mark.asyncio was deprecated in v0.23 in favor of loop_scope. Per the v2.0 milestone discussion on #1475, this PR converts the deprecation warning into a pytest.UsageError.

It takes the broader approach @seifertm suggested in the issue: any unrecognized keyword argument to the marker now raises a usage error, with no special-case handling for scope left in the parser. The error message names the offending kwargs by repr (e.g. 'scope', 'cope') rather than printing a generic "only loop_scope and loop_factories are accepted" sentence. Positional-argument validation is split into its own branch so its message can mention positionals specifically rather than lumping them in with unknown kwargs.

Surface-level details

• _validate_asyncio_marker now raises pytest.UsageError (was ValueError); the kwarg allow-set is {"loop_scope", "loop_factories"} with no "scope".
• _parse_asyncio_marker loses the if "scope" in kwargs: branch and the duplicate-loop_scope error path (which is now unreachable, since scope can no longer reach this function at all).
• PytestAsyncioFunction._loop_scope drops the or marker.kwargs.get("scope") fallback.
• The _MARKER_SCOPE_KWARG_DEPRECATION_WARNING and _DUPLICATE_LOOP_SCOPE_DEFINITION_ERROR strings are deleted.
• The v0.23 migration guide is updated to note that scope= is now an error rather than a warning.

Tests

• tests/markers/test_function_scope.py::test_warns_when_scope_argument_is_present removed; the existing test_raises_when_scope_and_loop_scope_arguments_are_present is extended with an fnmatch_lines assertion on the new "unexpected keyword argument 'scope'" message so the regression is pinned to the new error path.
• tests/markers/test_invalid_arguments.py: the three ValueError-asserting tests are updated to match the new UsageError message wording, and a new test_error_when_scope_keyword_argument_is_passed covers the lone-scope= case that was formerly only a deprecation warning.
• The targeted suite (tests/markers/test_function_scope.py + tests/markers/test_invalid_arguments.py, 20 tests) passes locally. The remaining 27 failures in python -m pytest on main are pre-existing subprocess-launch failures in my local environment and reproduce verbatim against an unmodified main checkout, so they're unrelated to this change.

Changelog

Added changelog.d/1475.removed.rst under the Removed category, since the kwarg is being removed in v2.0.

Notes

I deliberately left _INVALID_LOOP_FACTORIES_KWARG raising ValueError rather than UsageError — that's a value-shape check, not a kwarg-name check, and converting it felt out of scope for this issue. Happy to fold it in if you'd prefer the validators speak the same exception type.

[SaInekK]

Thanks for taking this on, @mokashang — the approach matches what @seifertm and I landed on in #1475 (UsageError for any unknown kwarg, dropping the scope special-casing), so this reads right to me.

One CI nit: the Run linters job is red on the shed hook, which wants to reformat tests/markers/test_invalid_arguments.py. Running pre-commit run --all-files locally should auto-fix it and turn the job green.

Splitting the positional-arg error out from the unknown-kwarg path is a nice touch. 👍

[mokashang]

Thanks @SaInekK — good catch. Pushed 53cfd58 collapsing the fnmatch_lines call onto one line; pre-commit run --all-files is clean locally and all 9 tests in test_invalid_arguments.py (plus the 11 in test_function_scope.py) still pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.48%. Comparing base (c23095a) to head (53cfd58).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1486      +/-   ##
==========================================
- Coverage   94.50%   94.48%   -0.03%     
==========================================
  Files           2        2              
  Lines         510      508       -2     
  Branches       62       61       -1     
==========================================
- Hits          482      480       -2     
  Misses         22       22              
  Partials        6        6              

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