Bug 191001 – REGRESSION(r237218): [GTK] Broke imported/w3c/web-platform-tests/intersection-observer/same-document-root.html

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKitGTK

[Michael Catanzaro]

r237218 "Flaky IntersectionObserver web platform tests involving style updates" broke layout test imported/w3c/web-platform-tests/intersection-observer/same-document-root.html. Text diff:

--- /home/slave/webkitgtk/gtk-linux-64-release-tests/build/layout-test-results/imported/w3c/web-platform-tests/intersection-observer/same-document-root-expected.txt
+++ /home/slave/webkitgtk/gtk-linux-64-release-tests/build/layout-test-results/imported/w3c/web-platform-tests/intersection-observer/same-document-root-actual.txt
@@ -1,9 +1,5 @@
 
-PASS IntersectionObserver in a single document with explicit root. 
-PASS First rAF 
-PASS document.scrollingElement.scrollTop = window.innerHeight. 
-PASS root.scrollTop = 150 with root scrolled into view. 
-PASS document.scrollingElement.scrollTop = 0. 
-PASS root.scrollTop = 0 
-PASS root.scrollTop = 150 with root scrolled out of view. 
+Harness Error (TIMEOUT), message = null
 
+TIMEOUT IntersectionObserver in a single document with explicit root. Test timed out
+

[Ali Juma]

Looking through the failures, the more common failure mode seems to be:
--- /home/slave/webkitgtk/gtk-linux-64-debug-tests/build/layout-test-results/imported/w3c/web-platform-tests/intersection-observer/same-document-root-expected.txt
+++ /home/slave/webkitgtk/gtk-linux-64-debug-tests/build/layout-test-results/imported/w3c/web-platform-tests/intersection-observer/same-document-root-actual.txt
@@ -4,6 +4,6 @@
 PASS document.scrollingElement.scrollTop = window.innerHeight. 
 PASS root.scrollTop = 150 with root scrolled into view. 
 PASS document.scrollingElement.scrollTop = 0. 
-PASS root.scrollTop = 0 
-PASS root.scrollTop = 150 with root scrolled out of view. 
+FAIL root.scrollTop = 0 assert_equals: entries.length expected 3 but got 2
+FAIL root.scrollTop = 150 with root scrolled out of view. assert_equals: entries.length expected 4 but got 2

In this case, |root| is an overflow scroller. What's happening is that after we scroll |root|, we're not getting the expected intersection observation by the time the next rAF happens. So either overflow scrolls don't trigger flushes on GTK, or they trigger flushes too late.

[Miguel Gomez]

This is flaky now. But there's https://bugs.webkit.org/show_bug.cgi?id=191001 that handles the flakyness of all the intersection-observer directory tests. So I'll just close this, remove its expectation, and let the other bug handle this flakyness as well.