Repair wp/6.5 branch Actions: Improve reliability of TinyMCE-related tests - #83466

Part of #82928.

What?

Replaces the meta box E2E test's iframe-presence wait with a wait on TinyMCE's own initialized flag, and adds the same wait after switching back to Visual mode. No change to what the test asserts.

Why?

test/e2e/specs/editor/plugins/wp-editor-meta-box.spec.js switches the meta box's TinyMCE instance out of Visual mode and types into the textarea. It guarded that switch with:

await page.locator( '#test_tinymce_id_ifr' ).waitFor();

That waits for the editor iframe element to be attached, which happens early in TinyMCE's startup — not at the end of it. The comment above it already claimed the intent was to wait "for it to initialize"; this makes the code actually do that.

When the mode switch lands inside that window, two things can go wrong: TinyMCE flips the editor back to Visual once initialization completes, discarding the typed text, and getSelection() can return null while TinyMCE restores the cursor position. Both surface as intermittent failures in end2end-test.yml.

Waiting on window.tinyMCE.get( 'test_tinymce_id' ).initialized closes the window, because that flag is set only after startup finishes. The bundled TinyMCE is 4.9.11 on every WordPress version these branches pin, and it defines window.tinyMCE, returns the instance from EditorManager.get( id ), and sets .initialized on it.

This is a straight port of 631bcb2 (#78631) from trunk. The mode-switch button name is branch-specific — WordPress renamed that tab from Text to Code in WordPress 6.8, and this branch pins its test WordPress accordingly — so the selector is deliberately left alone.

Use of AI Tools

This PR was created by Claude Code under my supervision. All code should be treated as AI-produced and not yet reviewed by a human until this PR is marked Ready for Review.

🤖 Generated with Claude Code