feat: add Choice field validator for categorical columns

[suhavani23]

Summary

Adds a Choice() field helper to arnio.schema that validates categorical columns against an explicit set of allowed values. Builds on the existing allowed validation logic in _validate_column. Raises ValueError if the allowed set is empty.

Linked issue

Fixes #194

Type of change

• Feature

Area

• Schema validation

Testing

• make test
• Added 8 tests in tests/test_schema.py covering valid choices, invalid choices, empty allowed set, nullable behavior, and different input types (list, tuple, set).

Contributor checklist

• I read the contributing guide.
• I kept the PR focused on one issue or one logical change.
• I added or updated tests for behavior changes.
• I added or updated docs/examples for public API changes.
• I checked that generated files, logs, and local build artifacts are not committed.
• My PR title uses Conventional Commits (feat:, fix:, docs:, test:, refactor:, chore:).

[suhavani23]

All CI checks passing. Ready for review! Fixes #194"

[im-anishraj]

Thanks @suhavani23 for the clean first pass on Choice. I rechecked the branch against current main; this needs another update before it can be merged.

Blockers:

• The branch now conflicts with current main in tests/test_schema.py after the latest schema work was merged.
• upstream_tests.txt appears to be an accidental binary/workspace artifact and should be removed from the PR.
• Please keep the tests focused and remove unused fixtures/imports where possible; for example, test_choice_valid_values takes sample_csv but then creates its own DataFrame.

Please rebase on latest main, remove the stray file, resolve the schema test conflict by preserving all existing tests, and keep the Choice additions additive.

[im-anishraj]

Thanks for rebasing, but this head still cannot be approved.

Blockers:

• CI is failing across lint, smoke tests, notebook smoke, and the Python matrix.
• upstream_tests.txt is still included as a stray workspace artifact and should be removed from the PR.
• The Choice helper appears inserted in the middle of the CountryCode section in arnio/schema.py, leaving the surrounding docstring/body malformed. Please place Choice as a standalone helper between complete function definitions.
• tests/test_schema.py has an unrelated assert result.bad_rows == [1, 3] added inside test_schema_json_roundtrip_preserves_fields_and_options, where result is not part of that test. Please remove that unrelated assertion and keep the new tests additive/focused.
• test_choice_valid_values still takes sample_csv and reads it before replacing frame with a pandas-created frame; please remove the unused fixture/read.

Please remove the artifact, fix the malformed schema/test edits, run Black/Ruff, and make sure CI is green before requesting another review.

[im-anishraj]

Hi @suhavani23, maintainer deadline update: please push the requested fixes/rebase or reply with your ETA by May 31, 2026 at 11:59 PM IST.

We are not closing this PR right now. This deadline is only to keep the active review queue organized and confirm which PRs are still being worked on. If this PR overlaps with already merged work or another open PR, please also clarify what unique change remains. Thanks.

[suhavani23]

Hey @im-anishraj , acknowledged! I'll have the fixes pushed by June 5. Thanks for the patience!

[vercel]

@suhavani23 is attempting to deploy a commit to the xtylishanish-gmailcom's projects Team on Vercel.

A member of the Team first needs to authorize it.

[im-anishraj]

Hi @suhavani23, thanks for pushing the update. I checked the latest head (�439c71) and this still needs fixes before it can be re-reviewed for merge.\n\nCurrent blockers from CI:\n\n- Black still fails and would reformat �rnio/frame.py, �rnio/schema.py, and ests/test_frame.py.\n- The Python test matrix fails on ests/test_website_api_docs.py::test_website_api_reference_mentions_public_exports because Choice is now exported publicly but is not documented in the website API reference.\n\nPlease run Black on the changed files and add the new Choice helper to the public API docs/website reference so the export coverage test passes. I also added status:blocked while these CI failures remain. Vercel is still an external authorization issue, but the lint/test failures above are contributor-side blockers.

[suhavani23]

Hi @im-anishraj — thanks for the review! I've addressed both blockers:

Ran Black on frame.py, schema.py, and test_frame.py — all reformatted and CI lint now passes
Added the Choice() field builder to the website API reference (website/api.html), so the public-exports doc check now passes too

All 48 checks are green except Vercel, which looks like it needs deploy authorization on your end. Ready for another look whenever you get a chance!