Bug 203157 – REGRESSION (~r251261): Layout Test scrollingcoordinator/ios/non-stable-viewport-scroll.html is a Flaky Failure

• Status: RESOLVED
• Resolution: CONFIGURATION CHANGED
• Component: Tools / Tests

[Russell Epstein]

The following layout test started failing with significantly increased frequency after the changes landed in r251262:

scrollingcoordinator/ios/non-stable-viewport-scroll.html

Steps to Reproduce:

run-webkit-tests --ios-simulator --no-retry --no-sample-on-timeout scrollingcoordinator/ios/non-stable-viewport-scroll.html --iter 100 --force

Test History:

https://results.webkit.org/?suite=layout-tests&test=scrollingcoordinator%2Fios%2Fnon-stable-viewport-scroll.html

Diff:

--- /Volumes/Data/slave/ios-simulator-13-release-tests-wk2/build/layout-test-results/scrollingcoordinator/ios/non-stable-viewport-scroll-expected.txt
+++ /Volumes/Data/slave/ios-simulator-13-release-tests-wk2/build/layout-test-results/scrollingcoordinator/ios/non-stable-viewport-scroll-actual.txt
@@ -2,30 +2,29 @@
 (GraphicsLayer
   (anchor 0.00 0.00)
   (bounds 320.00 5013.00)
-  (visible rect 0.00, 1000.00 106.67 x 182.67)
-  (coverage rect 0.00, 1000.00 106.67 x 182.67)
+  (visible rect 0.00, 817.50 320.00 x 548.00)
+  (coverage rect 0.00, 817.50 320.00 x 548.00)
   (intersects coverage rect 1)
-  (contentsScale 6.00)
+  (contentsScale 2.00)
   (children 1
     (GraphicsLayer
       (bounds 320.00 5013.00)
       (contentsOpaque 1)
-      (visible rect 0.00, 1000.00 106.67 x 182.67)
-      (coverage rect 0.00, 957.33 192.00 x 268.00)
+      (visible rect 0.00, 817.50 320.00 x 548.00)
+      (coverage rect 0.00, 689.50 576.00 x 804.00)
       (intersects coverage rect 1)
-      (contentsScale 6.00)
+      (contentsScale 2.00)
       (children 1
         (GraphicsLayer
           (position 10.00 0.00)
-          (approximate position 10.00 634.66)
+          (approximate position 10.00 817.50)
           (bounds 100.00 548.00)
-          (usingTiledLayer 1)
           (contentsOpaque 1)
           (drawsContent 1)
-          (visible rect 0.00, 365.34 96.67 x 182.66)
-          (coverage rect -10.00, 322.68 192.00 x 268.00)
+          (visible rect 0.00, 0.00 100.00 x 548.00)
+          (coverage rect -10.00, -128.00 576.00 x 804.00)
           (intersects coverage rect 1)
-          (contentsScale 6.00)
+          (contentsScale 2.00)
         )
       )
     )

[Radar WebKit Bug Importer]

<rdar://problem/56410921>

[Russell Epstein]

Marked test as flaky in r251288

[Simon Fraser (smfr)]

This is surprising given than r251262 should have only affected macOS.

[Alexey Proskuryakov]

I think that r251261 is the more likely culprit.

[Alexey Proskuryakov]

Not happening any more now that r251261 was reverted.