Bug 240037

Summary:	[ iOS ] css3/background/background-repeat-space-content.html is a flaky image failure
Product:	WebKit	Reporter:	Karl Rackler <rackler>
Component:	New Bugs	Assignee:	Karl Rackler <rackler>
Status:	NEW ---
Severity:	Normal	CC:	ap, simon.fraser, webkit-bot-watchers-bugzilla, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=238965

Description Karl Rackler 2022-05-03 14:06:38 PDT

Description:
css3/background/background-repeat-space-content.html

The first failure that I saw on the dashboard was 12/14/2021 at r287060, but this does not appear relevant to causing this issue.  This test seems to have been flaky since the start.

History:
https://results.webkit.org/?suite=layout-tests&test=css3%2Fbackground%2Fbackground-repeat-space-content.html&platform=ios&limit=50000

Image Diff:
https://build.webkit.org/results/Apple-iOS-15-Simulator-Release-WK2-Tests/250205@main%20(2446)/css3/background/background-repeat-space-content-diffs.html

Comment 1 Radar WebKit Bug Importer 2022-05-03 14:06:56 PDT

<rdar://problem/92692179>

Comment 2 Karl Rackler 2022-05-03 14:08:36 PDT

I have marked this test as a flaky image failure while this issue is investigated.

Comment 3 Karl Rackler 2022-05-03 14:15:00 PDT

Pull request: https://github.com/WebKit/WebKit/pull/480

Comment 4 EWS 2022-05-03 14:19:26 PDT

Test gardening commit r293739 (250227@main): <https://commits.webkit.org/250227@main>

Reviewed commits have been landed. Closing PR #480 and removing active labels.

Comment 5 Simon Fraser (smfr) 2022-05-03 14:53:42 PDT

r293447 didn't fix this?

Comment 6 Simon Fraser (smfr) 2022-05-03 15:04:29 PDT

For cases like this where the pixel differences are consistent, we should be using pixel tolerance to make them pass.

Example: r288449

Comment 7 Karl Rackler 2022-05-03 16:40:53 PDT

REPRODUCTION STEPS
I can reproduce this on ToT (r293740).

Command: 
run-webkit-tests --root 293740 --ios-simulator --exit-after-n-failures 1 --exit-after-n-crashes-or-timeouts 1 --details --debug-rwt-logging --pixel-tests --tolerance 0.10 --iterations 2000 --no-retry css3/background/background-repeat-space-content.html

Result:  
Unexpected flakiness: image-only failures (1)
  css3/background/background-repeat-space-content.html [ ImageOnlyFailure Pass ]

Comment 8 Alexey Proskuryakov 2022-05-03 16:44:53 PDT

How can this be flaky? We are just drawing the same circle.png in both actual and expected.