Tests: Add unit test coverage for Block Bindings core/term-data source

[huzaifaalmesbah]

This PR adds comprehensive unit test coverage for the Block Bindings core/term-data source (src/wp-includes/block-bindings/term-data.php) in tests/phpunit/tests/block-bindings/termDataSource.php.

The core/term-data source was introduced in r60946 (#64107) and updated in r60958 (#64112), but lacked a dedicated PHPUnit test file verifying its getter callback, boundary conditions, navigation block attribute fallbacks, permission checks, and source registration.

Trac ticket: https://core.trac.wordpress.org/ticket/65819

Changes & New Tests Added

1. Input validation & boundary checks:

   • test_get_value_returns_null_when_field_empty: Verifies null is returned when the field argument is omitted or empty (tested via data provider).
   • test_get_value_returns_null_when_context_empty: Verifies null is returned when required block context (termId or taxonomy) is missing or invalid.
   • test_get_value_returns_null_when_term_not_found: Confirms null return for non-existent terms.
   • test_get_value_returns_null_when_taxonomy_invalid: Confirms null return for invalid taxonomy names.
   • test_get_value_returns_null_for_unsupported_field: Confirms null return for unrecognized field keys.

2. Supported field value computation:

   • test_get_value_returns_supported_fields: Data provider testing name, slug, description, and count.
   • test_get_value_link_field: Tests term permalink generation via get_term_link().
   • test_get_value_id_and_parent_fields: Tests string casting and escaping for term ID and parent ID.

3. Navigation block compatibility:

   • test_get_value_navigation_link_attributes: Verifies reading id and type attributes for core/navigation-link.
   • test_get_value_navigation_submenu_attributes: Verifies reading attributes for core/navigation-submenu.
   • test_get_value_navigation_link_maps_tag_type_to_post_tag: Verifies UI shorthand tag mapping to post_tag taxonomy slug.
   • test_get_value_navigation_link_missing_attributes: Verifies null return when navigation attributes are missing.

4. Permissions & visibility:

   • test_get_value_non_publicly_queryable_taxonomy_unauthenticated: Verifies unauthenticated users cannot read private taxonomies.
   • test_get_value_non_publicly_queryable_taxonomy_with_read_capability: Verifies users with read capability can access private taxonomies.

5. Source registration & integration:

   • test_register_block_bindings_term_data_source: Verifies source registration metadata (label, uses_context).
   • test_register_block_bindings_term_data_source_idempotent: Verifies registration idempotence.
   • test_source_get_value_integration: Verifies end-to-end lookup through WP_Block_Bindings_Source::get_value().

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Testing Instructions

Run the unit test suite:

npm run test:php -- --filter Tests_Block_Bindings_Term_Data_Source

Run multisite:

npm run test:php -- --filter Tests_Block_Bindings_Term_Data_Source -c tests/phpunit/multisite.xml

Run the entire block-bindings test group:

npm run test:php -- --group block-bindings

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Use of AI Tools

AI assistance: Yes
Model(s): Gemini 3.8 Flash
Used for: Analyzing execution branches and edge cases in src/wp-includes/block-bindings/term-data.php, structuring test cases with data providers, and drafting this PR summary. All generated tests (28 tests, 34 assertions across single-site and multisite) and coding standards compliance were reviewed, executed, and verified locally in a Docker environment.

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Props huzaifaalmesbah, lancewillett.

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[lancewillett]

Optional follow-up for this PR: add markup/entity fixtures with literal expected output to protect name escaping and description sanitization. The current plain-text fixtures do not detect removal of those transformations.

[lancewillett]

PR #13981 landed in https://core.trac.wordpress.org/changeset/64086