Bug 243710 – REGRESSION (252720@main): [ iOS ] Four scrollingcoordinator/scrolling-tree/coordinated-frame tests are a consistent failure

• Component: New Bugs
• Status: RESOLVED FIXED

[Karl Rackler]

Description:
scrollingcoordinator/scrolling-tree/coordinated-frame-gain-scrolling-ancestor.html
scrollingcoordinator/scrolling-tree/coordinated-frame-in-fixed.html
scrollingcoordinator/scrolling-tree/coordinated-frame-lose-scrolling-ancestor.html
scrollingcoordinator/scrolling-tree/coordinated-frame.html

The first failure I saw on the dashboard was on 7/21/2022 at 252721@main.  The four tests are failing with similar diffs.  

REPRODUCTION STEPS
I can reproduce this on 252720@main but cannot reproduce it on 252719@main or earlier.

Command: 
run-webkit-tests --ipad-simulator --model 'iPad (5th generation)' --exit-after-n-failures 1 --exit-after-n-crashes-or-timeouts 1 --iterations 50 --no-retry scrollingcoordinator/scrolling-tree/coordinated-frame-gain-scrolling-ancestor.html

Result: 
Regressions: Unexpected text-only failures (1)
  scrollingcoordinator/scrolling-tree/coordinated-frame-gain-scrolling-ancestor.html [ Failure ]

History:
https://results.webkit.org/?suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&test=scrollingcoordinator%2Fscrolling-tree%2Fcoordinated-frame-gain-scrolling-ancestor.html&test=scrollingcoordinator%2Fscrolling-tree%2Fcoordinated-frame-in-fixed.html&test=scrollingcoordinator%2Fscrolling-tree%2Fcoordinated-frame-lose-scrolling-ancestor.html&test=scrollingcoordinator%2Fscrolling-tree%2Fcoordinated-frame.html&limit=50000&platform=ios&model=iPad%20(5th%20generation)

Diff:
--- /Volumes/Data/worker/Apple-iPadOS-15-Simulator-Debug-WK2-Tests/build/layout-test-results/scrollingcoordinator/scrolling-tree/coordinated-frame-gain-scrolling-ancestor-expected.txt
+++ /Volumes/Data/worker/Apple-iPadOS-15-Simulator-Debug-WK2-Tests/build/layout-test-results/scrollingcoordinator/scrolling-tree/coordinated-frame-gain-scrolling-ancestor-actual.txt
@@ -10,6 +10,8 @@
   (layout viewport at (0,0) size 800x600)
   (min layout viewport origin (0,0))
   (max layout viewport origin (0,416))
+  (synchronous event dispatch region for event wheel
+    at (45,47) size 404x304)
   (behavior for fixed 0)
   (children 1
     (Fixed node
@@ -31,29 +33,7 @@
               (min layout viewport origin (0,0))
               (max layout viewport origin (0,120))
               (behavior for fixed 0)
-              (children 2
-                (Overflow scrolling node
-                  (scrollable area size 400 300)
-                  (contents size 400 1760)
-                  (scrollable area parameters
-                    (horizontal scroll elasticity 1)
-                    (vertical scroll elasticity 1)
-                    (horizontal scrollbar mode 0)
-                    (vertical scrollbar mode 0)
-                    (allows vertical scrolling 1))
-                  (children 1
-                    (Sticky node
-                      (anchor edges: AnchorEdgeTop AnchorEdgeBottom)
-                      (top offset 10.00)
-                      (bottom offset 10.00)
-                      (containing block rect at (0,0) size 400x1760)
-                      (sticky box rect at (0,830) size 100x100)
-                      (constraining rect at (0,0) size 400x300)
-                      (sticky offset at last layout width=0 height=-640)
-                      (layer position at last layout (0,190))
-                    )
-                  )
-                )
+              (children 1
                 (Sticky node
                   (anchor edges: AnchorEdgeTop AnchorEdgeBottom)
                   (top offset 10.00)

[Radar WebKit Bug Importer]

<rdar://problem/98356321>

[Karl Rackler]

Update description:
This affects [iOS] on model iPad (5th generation) only.

[Karl Rackler]

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

[EWS]

Test gardening commit 253248@main (650ee1c49d6b): <https://commits.webkit.org/253248@main>

Reviewed commits have been landed. Closing PR #3134 and removing active labels.

[EWS]

Test gardening commit 253252@main (ce905cce96b7): <https://commits.webkit.org/253252@main>

Reviewed commits have been landed. Closing PR #3135 and removing active labels.

[Sam Sneddon [:gsnedders]]

These tests have <!-- webkit-test-runner [ AsyncOverflowScrollingEnabled=true ] -->, but only within the resources/doc-with-sticky.html subresource, which never worked, but it worked because incidentally `-webkit-overflow-scrolling` was accidentally exposed regardless of settings.

[Karl Rackler]

(In reply to Sam Sneddon [:gsnedders] from comment #6)
> These tests have <!-- webkit-test-runner [
> AsyncOverflowScrollingEnabled=true ] -->, but only within the
> resources/doc-with-sticky.html subresource, which never worked, but it
> worked because incidentally `-webkit-overflow-scrolling` was accidentally
> exposed regardless of settings.

I also see test fast/scrolling/ios/overflow-scroll-inherited.html consistently failing after 252720@main. 

Diff: 
--- /Volumes/Data/worker/Apple-iPadOS-15-Simulator-Debug-WK2-Tests/build/layout-test-results/fast/scrolling/ios/overflow-scroll-inherited-expected.txt
+++ /Volumes/Data/worker/Apple-iPadOS-15-Simulator-Debug-WK2-Tests/build/layout-test-results/fast/scrolling/ios/overflow-scroll-inherited-actual.txt
@@ -1,5 +1,2 @@
-test1 -webkit-overflow-scrolling: auto
-test2 -webkit-overflow-scrolling: auto
-test3 -webkit-overflow-scrolling: auto
-test4 -webkit-overflow-scrolling: auto
+CONSOLE MESSAGE: TypeError: null is not an object (evaluating 'cssValue.cssText')

History:
https://results.webkit.org/?suite=layout-tests&test=fast%2Fscrolling%2Fios%2Foverflow-scroll-inherited.html&model=iPad%20(5th%20generation)


Would the root of this failure be the same cause, or is it a different issue?

[Sam Sneddon [:gsnedders]]

Pull request: https://github.com/WebKit/WebKit/pull/3152

[Sam Sneddon [:gsnedders]]

(In reply to Karl Rackler from comment #7)
> Would the root of this failure be the same cause, or is it a different issue?

Same issue.

[EWS]

Committed 253361@main (c7f9e1da3dd8): <https://commits.webkit.org/253361@main>

Reviewed commits have been landed. Closing PR #3152 and removing active labels.