Bug 308086 – [Tahoe arm64] compositing/visible-rect/animated-from-none.html is a flaky text failure

• Status: RESOLVED
• Resolution: FIXED
• Component: Animations

[Diego De La Toba]

compositing/visible-rect/animated-from-none.html is a flaky text failure on macOS Tahoe arm64 release.


HISTORY:
https://results.webkit.org/?suite=layout-tests&test=compositing%2Fvisible-rect%2Fanimated-from-none.html


TEXT DIFF:
--- /Volumes/Data/worker/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/build/layout-test-results/compositing/visible-rect/animated-from-none-expected.txt
+++ /Volumes/Data/worker/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/build/layout-test-results/compositing/visible-rect/animated-from-none-actual.txt
@@ -35,7 +35,6 @@
                   (position -100.00 0.00)
                   (bounds 200.00 200.00)
                   (contentsOpaque 1)
-                  (transform [1.00 0.00 0.00 0.00] [0.00 1.00 0.00 0.00] [0.00 0.00 1.00 0.00] [0.00 0.00 0.00 1.00])
                   (visible rect 100.00, 0.00 100.00 x 200.00)
                   (coverage rect 100.00, 0.00 500.00 x 200.00)
                   (intersects coverage rect 1)


DIFF URL:
https://build.webkit.org/results/Apple-Tahoe-Release-AppleSilicon-WK2-Tests/307719%40main%20(1758)/compositing/visible-rect/animated-from-none-pretty-diff.html


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

run-webkit-tests --release --force --no-retry --iterations 2000 -f compositing/visible-rect/animated-from-none.html

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

[Radar WebKit Bug Importer]

<rdar://problem/170589380>

[Diego De La Toba]

Pull request: https://github.com/WebKit/WebKit/pull/58878

[EWS]

Test gardening commit 307731@main (83d56e0bd8cb): <https://commits.webkit.org/307731@main>

Reviewed commits have been landed. Closing PR #58878 and removing active labels.

[Diego De La Toba]

Upon further investigation this does NOT look like a test issue.
"animation.ready" should guarantee the first frame has been rendered, meaning the transform should be applied by the time it resolves.

The transform is sometimes missing after ready resolves, thus appears to be a WebKit rendering bug. The test is correct - it expects the transform to be present after ready resolves, as the spec requires.

https://www.w3.org/TR/web-animations-1/#dom-animation-ready: "the user agent has completed any setup required to begin the playback of the animation's associated effect including rendering the first frame"

[Antoine Quint]

I can't reproduce the failure locally with a debug build. Will try a release build next since that's what Diego used in his sample command.

[Antoine Quint]

Most likely this will need to be updated to use `await acceleratedAnimation(animation)` rather than `await animation.ready` to ensure that the threaded animation is running.

[Diego De La Toba]

I will implement those changes and see if I can reproduce.

[Diego De La Toba]

Pull request: https://github.com/WebKit/WebKit/pull/58967

[EWS]

Committed 307820@main (d01c2d50dc76): <https://commits.webkit.org/307820@main>

Reviewed commits have been landed. Closing PR #58967 and removing active labels.