Bug 308586 – [macOS] imported/w3c/web-platform-tests/fullscreen/rendering/fullscreen-pseudo-class.html is a flaky text failure

• Component: New Bugs
• Status: REOPENED

[Diego De La Toba]

imported/w3c/web-platform-tests/fullscreen/rendering/fullscreen-pseudo-class.html is a flaky text failure on macOS


HISTORY:
https://results.webkit.org/?suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Ffullscreen%2Frendering%2Ffullscreen-pseudo-class.html


DIFF:
--- /Volumes/Data/Builds/Mac/Production/TestBuild308142@main/layout-test-results/imported/w3c/web-platform-tests/fullscreen/rendering/fullscreen-pseudo-class-expected.txt
+++ /Volumes/Data/Builds/Mac/Production/TestBuild308142@main/layout-test-results/imported/w3c/web-platform-tests/fullscreen/rendering/fullscreen-pseudo-class-actual.txt
@@ -1,3 +1,5 @@
 
-PASS :fullscreen pseudo-class
+Harness Error (TIMEOUT), message = null
 
+TIMEOUT :fullscreen pseudo-class Test timed out
+


DIFF URL:
https://build.webkit.org/results/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/308141%40main%20(1951)/imported/w3c/web-platform-tests/fullscreen/rendering/fullscreen-pseudo-class-pretty-diff.html


REPRODUCTION:
I was able to reproduce this failure on macOS Tahoe 26.2 arm64 release with the following:

run-webkit-tests --no-retry --force --expect-pass --iterations 50 imported/w3c/web-platform-tests/fullscreen/rendering/fullscreen-pseudo-class.html

I am going to mark expectations as pass fail while this pends investigation.

[Radar WebKit Bug Importer]

<rdar://problem/171112681>

[Diego De La Toba]

Pull request: https://github.com/WebKit/WebKit/pull/59367

[EWS]

Test gardening commit 308151@main (d8ad0835333d): <https://commits.webkit.org/308151@main>

Reviewed commits have been landed. Closing PR #59367 and removing active labels.

[Diego De La Toba]

It appears the timeout message in the text diff is caused by fullscreen-pseudo-class.html:20-21 where we have the following sequential awaits:

await trusted_request(outer);
await fullScreenChange(); 

await trusted_request(outer) requests the full screen change (trusted-click.js:30 requestFullscreen()) then await fullScreenChange() registers the fullscreen change listener(trusted-click.js:41). I think what is happening here is requestFullscreen() completes before addEventListener ever runs causing the listener to wait forever.

The fix would be to use Promise.all() to register the listener before the request is made:

await Promise.all([fullScreenChange(), trusted_request(outer)]);

I'll put this fix up as a PR.

[Diego De La Toba]

Pull request: https://github.com/WebKit/WebKit/pull/59368

[EWS]

Committed 308351@main (9dbb511485aa): <https://commits.webkit.org/308351@main>

Reviewed commits have been landed. Closing PR #59368 and removing active labels.

[Mike Wyrzykowski]

Re-opening for pull request https://github.com/WebKit/WebKit/pull/59602