Tests: Fix two widget tests that depend on test order

[lancewillett]

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

Two widget tests pass in default order and fail when run alone, in reverse or in random order. One commit each:

• Tests_Widgets::test_retrieve_widgets_for_customizer()
  • In Customizer mode, retrieve_widgets() works on the $sidebars_widgets global and only checks that the theme mod is an array.
  • The test set the theme mod but never the global. It passed only because the test before it in the file left matching widgets cached; run alone, it read the default install widgets.
  • The test now sets the global to the same widgets, as the sibling retrieve_widgets() tests do.
• Tests_Widgets_wpWidgetMedia::test_constructor()
  • test_constructor_in_customize_preview() leaves $wp_customize set. The next WP_Widget_Media then thinks it is in a preview and adds a wp_enqueue_scripts hook the constructor test says should not be there.
  • The class now resets $wp_customize in clean_up_global_scope(), as Tests_Widgets_wpWidgetText already does.

No assertions changed.

Testing Instructions

1. Start the environment: npm run env:start && npm run env:install.
2. Run npm run test:php -- --filter '/^Tests_Widgets::test_retrieve_widgets_for_customizer( |$)/'. On trunk: fails ("Failed asserting that an array contains 'tag_cloud-1'"). On this branch: passes.
3. Run npm run test:php -- --filter 'Tests_Widgets_wpWidgetMedia::' --order-by=reverse. On trunk: test_constructor fails. On this branch: 12 tests pass.
4. Run npm run test:php -- --group widgets in default order and with --order-by=random --random-order-seed=1 and =2. On trunk, both tests fail at seeds 1 and 2. On this branch, neither does. Other REST widget tests in that group still fail at those seeds; Tests: Improve REST API test isolation #13185 addresses those.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code, Codex
Model(s): Claude Opus 5.5, gpt-6-astra (Codex review)
Used for: tracing both failures, making the changes, running the tests, and a second-model review

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[Copilot]

Copilot review overview

🟢 Approval recommended

Both changes correctly eliminate the identified test-order dependencies using established test patterns.

Review effort: Balanced
Findings: None

What changed in this PR

Fixes order-dependent widget tests by isolating their global state.

Changes:

• Initializes $sidebars_widgets in the Customizer test.
• Resets $wp_customize after media-widget tests.

File	Description
tests/​phpunit/​tests/​widgets.php	Initializes the sidebar global used by retrieve_widgets().
tests/​phpunit/​tests/​widgets/​wpWidgetMedia.php	Cleans up the Customizer global between tests.

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[lancewillett]

PR #13863 landed in https://core.trac.wordpress.org/changeset/64038