Bug 288005 – [ macOS WK2 ] imported/w3c/web-platform-tests/css/selectors/invalidation/nth-last-child-in-shadow-root.html is a flaky ImageOnlyFailure

• Status: NEW
• Component: CSS

[Robert Jenner]

imported/w3c/web-platform-tests/css/selectors/invalidation/nth-last-child-in-shadow-root.html

is a flaky ImageOnly Failure for macOS WK2. As of this filing this appeared to be a very very flaky test failure on WK2 on Ventura and up. 

HISTORY:
https://results.webkit.org/?suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fcss%2Fselectors%2Finvalidation%2Fnth-last-child-in-shadow-root.html

IMAGE DIFF URL:
https://build.webkit.org/results/Apple-Sequoia-Release-WK2-Tests/290604@main%20(1682)/imported/w3c/web-platform-tests/css/selectors/invalidation/nth-last-child-in-shadow-root-diff.png

Image is off by .09% 

Images will be attached to this bug.

[Robert Jenner]

Looking at the ImageDiffs it looks worse than being off my .09% 

"Should be Red" shows up in green, and "Should be Green" doesn't show up at all.

[Radar WebKit Bug Importer]

<rdar://problem/145168324>

[Robert Jenner]

Created attachment 474290 [details]
Image Diff files

[Robert Jenner]

I was able to reproduce this failure very easily on macOS Sequoia Production ToT running the test as follows:

run-webkit-tests imported/w3c/web-platform-tests/css/selectors/invalidation/nth-last-child-in-shadow-root.html --iterations 100

When running in 100 iterations it only passed 3 times, and failed 97 times.

[EWS]

Test gardening commit 290646@main (47f2ffeda280): <https://commits.webkit.org/290646@main>

Reviewed commits have been landed. Closing PR #40898 and removing active labels.

[Fujii Hironori]

imported/w3c/web-platform-tests/css/selectors/invalidation/nth-child-in-shadow-root.html is also flaky.
https://results.webkit.org/?suite=layout-tests&suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fcss%2Fselectors%2Finvalidation%2Fnth-child-in-shadow-root.html&test=imported%2Fw3c%2Fweb-platform-tests%2Fcss%2Fselectors%2Finvalidation%2Fnth-last-child-in-shadow-root.html