Exercise enclosure-like values without skipped tests

[claell]

Summary

• Replace enclosure-like value skips with explicit assertions.
• Verify removal values and removed_enclosing metadata across the full matrix.
• Assert exact output when addition is configured with no-enclosing.

Closes #579.

Validation

• pytest -p no:cacheprovider -W error tests/middleware_tests/test_enclosing.py: 926 passed, with no skips.
• Complete upstream test suite: 2,586 passed, 2 skipped, with the four existing deprecation warnings in tests/test_entrypoint.py.
• Complete pre-commit hook suite: passed.

Review note

This is a test-only change. The key judgment is that values beginning and ending with enclosure characters remain valid cases to test: removal interprets those boundary characters as enclosure, while addition configured with no-enclosing adds nothing and should be checked by exact equality.

AI assistance

This pull request was prepared with ChatGPT Codex using GPT-5.6 Sol with high reasoning effort. Codex assisted with test-matrix analysis, branch isolation, and validation. Automated validation is not a substitute for maintainer review.

[MiWeiss]

Hi @claell — same note across all of your July 16 issues and PRs (#567–#597), apologies for the repetition.

Closing this. Passing CI isn't evidence the underlying claim is real — it just means generated tests match generated code. The batch's timing, structure, and forward-referenced numbers point to this being AI-generated rather than manually found and checked, and reviewing it properly would take more effort than a targeted pass over the parser myself.

If this fixes something you actually hit: open a small, human-verified PR against a reopened issue with a real repro, and I'll review it in good faith. Any nontrivial design or API choice needs to be discussed and agreed first, not decided inside a PR. Please disclose and verify AI-assisted work before submitting going forward.