Tests: Isolate user fixtures from randomized execution

[sirreal]

Avoid mutating shared user IDs, refresh the shared capability fixture, and isolate the capability test that defines DISALLOW_UNFILTERED_HTML. Also restrict the INFORMATION_SCHEMA lookup to the active database so it cannot read another test database's auto-increment value.

The constant test has its own file and class, Tests_User_MapMetaCapDisallowUnfilteredHtml, so PHPUnit discovers it when invoked by file. A separate process prevents the constant from affecting later tests. A separate class prevents the child process's class teardown from deleting fixtures still needed by Tests_User_MapMetaCap in the parent process. The isolated test creates its own administrator and grants super-admin privileges on multisite; test teardown rolls back that grant.

Verified locally on 2026-09-14 with PHP 8.5.10 and PHPUnit 9.6.36:

• Both capability files pass when invoked individually on single site and multisite: the isolated file runs 1 test with 5 assertions; the original runs 35 tests with 95 assertions on single site and 96 on multisite.
• Randomized user group with seed 1789039001: 1,344 tests / 4,534 assertions on single site and 1,403 / 5,000 on multisite. Both exit 0 with five existing PHPUnit deprecation warnings; single site also has one skip.
• PHPCS passes on both files changed by the split. git diff --check passes.

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

[lancewillett]

Updated with 38efccb after merging current trunk.

The separate-process capability test previously passed user ID 0 to map_meta_cap(). On multisite, that user is not a super admin, so file-management capabilities map to do_not_allow instead of the test’s original expected primitive capabilities. The test now creates an administrator fixture, grants it super-admin privileges on multisite, and revokes those privileges in finally.

Validation:

• PHPCS: all four changed user test files
• Multisite mapMetaCap.php: 35 tests, 96 assertions
• Multisite randomized replay of the four changed user test files (seed 65893): 763 tests, 3,136 assertions
• Single-site randomized replay of the same files (seed 65894): 753 tests, 2,903 assertions
• PHP syntax checks and git diff --check

[github-actions]

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[lancewillett]

https://core.trac.wordpress.org/changeset/63614