Build/Test Tools: Reset shared state in the base test case instead of per test file

[sirreal]

Summary

A proposal, split out from the review of WordPress#13182–WordPress#13196 so it can be judged on its own.

Across those fifteen PRs the same shape kept recurring: the leak was fixed in the consumer, not the producer. Four of the local patches are symptoms of gaps in the shared fixture itself, so they are proposed here as one framework change to WP_UnitTestCase_Base instead of fifteen local ones.

Each change is a separate commit so any subset can be dropped.

#	Change	Gap it closes
1	Reset the metadata lazyload queue in set_up()	tear_down() already resets it, but wpSetUpBeforeClass() runs outside any test's tear_down(), so fixture-queued items leak into the class's first test
2	Add comment to the reset comment globals	comment_alt/comment_depth/comment_thread_alt were reset; comment was not. get_comment() falls back to that global
3	Reset $_SERVER in tear_down()	set_up() resets it, but class fixtures run before a class's first set_up(), so HTTPS etc. from a previous class are live while fixtures are built
4	Capture $ignore_files in set_up_before_class()	It was captured on the first set_up(), i.e. after the first class's fixtures had already uploaded — permanently exempting those files from remove_added_uploads()

On (4): the check is against null, not falsiness. An empty uploads directory is a legitimate captured state; with a falsy check the scan repeats at every class boundary and pins files left behind by earlier classes. Getting this wrong made residue worse (34 leftover files vs. 2) before it was corrected — see Verification.

Verification

Full local suite, single site, PHP 8.4 / MySQL. Each arm started from an identical empty uploads directory, since residue otherwise carries between runs and corrupts the comparison.

Ordering	trunk	with this PR
Default	1 failure, 4,559,413 assertions, 48 leftover upload files	1 failure, 4,559,413 assertions, 0 leftover files
--order-by=reverse	129 failures, 15 errors	128 failures, 15 errors
--order-by=random --random-order-seed=20260820	82 failures, 12 errors, 2 leftover files	82 failures, 12 errors, 0 leftover files

• Fixed: Tests_Comment_GetCommentAuthorUrlLink::test_no_comment (reverse order). Reproduced in isolation first: --order-by=reverse on that file alone fails on trunk, passes with this change.
• Newly broken: none, in any of the three orderings.
• The single default-order failure (Tests_Theme_ThemeDir::test_broken_themes) is a pre-existing local environment artifact — a stray html directory in the themes folder — and is present identically before and after.
• phpcs --standard=phpcs.xml.dist clean; php -l clean; git diff --check clean.

Honest limitations

• Multisite was not run locally. Two of the sibling PRs went red on multisite only, and this touches the shared base class, so multisite CI is the real gate here.
• Changes 1 and 3 produced no measurable difference in any of the three orderings tested. They close the wpSetUpBeforeClass() window by symmetry with resets that already exist, but they are defensive rather than evidenced. Reviewers may reasonably want them dropped or held until a failing ordering is demonstrated.
• Change 4 is what accounts for the leftover-file improvement (48 → 0 default, 2 → 0 random). Note that no current test class both uploads in wpSetUpBeforeClass() and calls remove_added_uploads(); the effect is cross-class, via the shared static.
• Change 4 makes scan_user_uploads() and files_in_dir() static so they can be called from set_up_before_class(). Both are used only inside abstract-testcase.php in core, and $this->files_in_dir() calls keep working — but a downstream suite that overrides either as a non-static method would fatal. That is the main back-compat question worth a decision.

Relationship to the sibling PRs

Change 2 makes the local tear_down() in WordPress#13186 redundant. The others overlap in spirit with the resets proposed in WordPress#13188, WordPress#13190, WordPress#13193 and WordPress#13194 but do not conflict textually with any of them.

Use of AI Tools

This change was written with Claude Code. The diagnosis, the patch, and every measurement in the Verification table were produced and checked by the agent; the numbers above come from actual local suite runs, not estimates.

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

🤖 Generated with Claude Code

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