Bug 308259 – [macOS] imported/w3c/web-platform-tests/fullscreen/rendering/ua-style-iframe.html is a flaky text failure.

• Component: New Bugs
• Status: RESOLVED FIXED

[Diego De La Toba]

imported/w3c/web-platform-tests/fullscreen/rendering/ua-style-iframe.html is a flaky text failure


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


DIFF:
--- /Volumes/Data/worker/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/build/layout-test-results/imported/w3c/web-platform-tests/fullscreen/rendering/ua-style-iframe-expected.txt
+++ /Volumes/Data/worker/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/build/layout-test-results/imported/w3c/web-platform-tests/fullscreen/rendering/ua-style-iframe-actual.txt
@@ -1,3 +1,5 @@
 
-PASS User-agent levels style sheet defaults for iframe
+Harness Error (TIMEOUT), message = null
 
+TIMEOUT User-agent levels style sheet defaults for iframe Test timed out
+


DIFF URL:
https://build.webkit.org/results/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/307853%40main%20(1814)/imported/w3c/web-platform-tests/fullscreen/rendering/ua-style-iframe-pretty-diff.html

REPRODUCTION
I was able to reproduce the failure with the following on macOS Tahoe ToT with the following:

run-webkit-tests --no-build --no-retry --no-show-results --exit-after-n-failures=1 --expect-pass --iterations=1000 --force -f --clobber-old-results --release imported/w3c/web-platform-tests/fullscreen/rendering/ua-style-iframe.html

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

[Radar WebKit Bug Importer]

<rdar://problem/170764288>

[Diego De La Toba]

Pull request: https://github.com/WebKit/WebKit/pull/59042

[EWS]

Test gardening commit 307869@main (88f46cfeed51): <https://commits.webkit.org/307869@main>

Reviewed commits have been landed. Closing PR #59042 and removing active labels.

[Diego De La Toba]

It appears the timeout message in the text diff is caused by ua-style-iframe.html:51-52 where we have the following sequential awaits:

await trusted_request(iframe);
await fullScreenChange(); 

await trusted_request(iframe) 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.

[Diego De La Toba]

The following resolves the flake:
Modify ua-style-iframe.html:51-52 to await Promise.all([trusted_request(iframe), fullScreenChange()]);
This ensures the listener is registered before the event fires during the fullscreen transition.

I am going to create a PR for this. Please review.

[Diego De La Toba]

Pull request: https://github.com/WebKit/WebKit/pull/59046

[EWS]

Committed 307923@main (793de962fdf2): <https://commits.webkit.org/307923@main>

Reviewed commits have been landed. Closing PR #59046 and removing active labels.