svg/animations/animateMotion-additive-2a.svg and svg/animations/animateMotion-additive-2b.svg sometimes fail with a very small difference

• Component: Tools / Tests
• Status: NEW ---

[Alexey Proskuryakov]

These tests are somewhat frequently reported as "image failure".

http://webkit-test-results.appspot.com/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=svg%2Fanimations%2FanimateMotion-additive-2a.svg
http://webkit-test-results.appspot.com/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=svg%2Fanimations%2FanimateMotion-additive-2b.svg

I can't actually see the difference, even on a difference image, and even when re-computing a difference it in a graphic editor. Weird.

[Alexey Proskuryakov]

Created attachment 243563 [details]
actual

[Alexey Proskuryakov]

Created attachment 243564 [details]
expected

[Alexey Proskuryakov]

> even when re-computing a difference it in a graphic editor

Another editor shows a very small color difference. I wonder if this has anything to do with how alpha is applied.

[Alexey Proskuryakov]

Marked as flaky in r180462.

[Truitt Savell]

Looks like we are seeing the same behavior with:
svg/animations/animateMotion-additive-2c.svg
svg/animations/animateMotion-additive-2d.svg

created new bug https://bugs.webkit.org/show_bug.cgi?id=187345
to mark tests as flakey

[Truitt Savell]

I reproduced the flakiness locally for all four tests. I ran the test for 500 iterations each, and they all fail roughly 1/5th of the time.

[Radar WebKit Bug Importer]

<rdar://problem/42793081>