Bug 194425 – REGRESSION: Layout Test fast/viewport/ios/device-width-viewport-after-changing-view-scale.html is a flaky failure

• Component: New Bugs
• Status: NEW

[Ryan Haddad]

The following layout test is failing on iOS

fast/viewport/ios/device-width-viewport-after-changing-view-scale.html

Probable cause:

Unknown.

Flakiness Dashboard:

https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=fast%2Fviewport%2Fios%2Fdevice-width-viewport-after-changing-view-scale.html

--- /Volumes/Data/slave/ios-simulator-12-release-tests-wk2/build/layout-test-results/fast/viewport/ios/device-width-viewport-after-changing-view-scale-expected.txt
+++ /Volumes/Data/slave/ios-simulator-12-release-tests-wk2/build/layout-test-results/fast/viewport/ios/device-width-viewport-after-changing-view-scale-actual.txt
@@ -1,7 +1,7 @@
 setViewScale(0.50)
-window size: [640, 1096]
+window size: [320, 548]
 square size: [64, 110]
-zoom scale: 0.50
+zoom scale: 1.00
 
 setViewScale(0.75)
 window size: [427, 731]

[Ryan Haddad]

This test appears to have recently become a flaky failure on the bots. It has come up as a false positive on EWS a few times in the last two days:
https://bugs.webkit.org/buglist.cgi?quicksearch=fast%2Fviewport%2Fios%2Fdevice-width-viewport-after-changing-view-scale.html&list_id=4477417

[Ryan Haddad]

I was able to reproduce the failure quickly with:
run-webkit-tests --ios-simulator fast/viewport/ios/device-width-viewport-after-changing-view-scale.html --iter 25 --exit-after-n-failures 1

[Ryan Haddad]

The earliest failure visible on the dashboard is from 1/21/2019, but the frequency of failures greatly increased on 2/3/2019.

[Radar WebKit Bug Importer]

<rdar://problem/47966485>