[rejaulalomkhan]

Description

In Tests_Sitemaps_wpSitemapsTaxonomies (tests/phpunit/tests/sitemaps/wpSitemapsTaxonomies.php), test_sitemap_does_not_404_for_valid_sitemap_subtypes() registers a custom taxonomy (valid_custom_taxonomy) without unregistering it in tear_down().

While other test-specific taxonomies (test_taxonomy, private_taxonomy, non_queryable_tax, public_taxonomy, non_queryable_taxonomy) are accounted for in teardown, valid_custom_taxonomy leaks into global registries, causing potential test pollution for subsequent test classes in the test suite.

This PR adds unregister_taxonomy( 'valid_custom_taxonomy' ) to tear_down() in Tests_Sitemaps_wpSitemapsTaxonomies.

Testing Instructions

1. Run vendor/bin/phpunit tests/phpunit/tests/sitemaps/wpSitemapsTaxonomies.php -> PASS (10 tests, 26 assertions).
2. Run vendor/bin/phpunit -c tests/phpunit/multisite.xml tests/phpunit/tests/sitemaps/wpSitemapsTaxonomies.php -> PASS (10 tests, 26 assertions).
3. Run vendor/bin/phpcs tests/phpunit/tests/sitemaps/wpSitemapsTaxonomies.php -> PASS (0 errors, 0 warnings).

Trac ticket: https://core.trac.wordpress.org/ticket/65893

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

Use of AI Tools

• Tool: Antigravity
• Model: Gemini 3.8 Flash
• Used for: Identified the missing custom taxonomy unregistration in wpSitemapsTaxonomies.php teardown, updated tear_down(), verified tests locally, and prepared the patch. I reviewed every line, ran the tests listed above, and take responsibility for the change.

[github-actions]

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Props rejaulalomkhan.

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[Copilot]

🟢 Approval recommended

There are no active review issues for the taxonomy teardown cleanup intended to improve test isolation.

No open issues 🎉

What changed in this PR

This PR improves test isolation in the sitemap taxonomy tests by cleaning up valid_custom_taxonomy after each test.

Changes:

• Adds unregister_taxonomy( 'valid_custom_taxonomy' ) to tear_down(), alongside the existing taxonomy cleanup.

File	Description
tests/​phpunit/​tests/​sitemaps/​wpSitemapsTaxonomies.php	Unregisters the custom taxonomy during teardown to prevent test pollution.

_{Review effort: Balanced}

[lancewillett]

Closing this cleanup-only proposal after tracing the shared Core test lifecycle. The inherited setup resets valid_custom_taxonomy before the next test; these fixtures do not opt out and are not built-in registrations. Class setup runs before that reset, but the inspected existing class fixtures reveal no failing consumer that needs this addition. Benefit unproven; green runs alone demonstrate compatibility, not an isolation fix. We can reconsider a minimal fix if an existing test/order fails without it. Thank you for investigating test isolation.

_{AI review · gpt-6}