Bug 184609 – REGRESSION: Layout Test platform/mac/media/audio-session-category-video-track-change.html is a flaky failure

• Status: NEW
• Component: Media

[Ryan Haddad]

The following layout test is flaky on macOS

platform/mac/media/audio-session-category-video-track-change.html

Probable cause:

Unknown, this test became flaky within the last 7 days. The first failure on the dashboard blames https://trac.webkit.org/changeset/230365/webkit

Flakiness Dashboard:

https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=platform%2Fmac%2Fmedia%2Faudio-session-category-video-track-change.html

--- /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/platform/mac/media/audio-session-category-video-track-change-expected.txt
+++ /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/platform/mac/media/audio-session-category-video-track-change-actual.txt
@@ -2,16 +2,16 @@
 RUN(internals.settings.setShouldManageAudioSessionCategory(true))
 RUN(video.src = findMediaFile("video", "../../../media/content/test"))
 EVENT(canplay)
-EXPECTED (internals.audioSessionCategory() == 'None') OK
+EXPECTED (internals.audioSessionCategory() == 'None'), OBSERVED 'AmbientSound' FAIL
 RUN(video.audioTracks[0].enabled = false)
 EVENT(change)
-EXPECTED (internals.audioSessionCategory() == 'None') OK
+EXPECTED (internals.audioSessionCategory() == 'None'), OBSERVED 'AmbientSound' FAIL
 RUN(video.muted = false)
 EVENT(volumechange)
-EXPECTED (internals.audioSessionCategory() == 'None') OK
+EXPECTED (internals.audioSessionCategory() == 'None'), OBSERVED 'AmbientSound' FAIL
 RUN(video.play())
 EVENT(playing)
-EXPECTED (internals.audioSessionCategory() == 'None') OK
+EXPECTED (internals.audioSessionCategory() == 'None'), OBSERVED 'AmbientSound' FAIL
 RUN(video.audioTracks[0].enabled = true)
 EVENT(change)
 EXPECTED (internals.audioSessionCategory() == 'MediaPlayback') OK

[Radar WebKit Bug Importer]

<rdar://problem/39878966>

[Ryan Haddad]

Marked test as flaky in https://trac.webkit.org/changeset/231462/webkit

[Ryan Haddad]

The test is still flaky, with most failures occurring on High Sierra.

[Truitt Savell]

This test has changed from being a constant failure to having flakey Crashes. The test started passing at https://trac.webkit.org/changeset/234463/webkit. 

Investigating Crashes

[Jer Noble]

Crash points to this assert in FrameView.cpp:602:

    if (!RuntimeEnabledFeatures::sharedFeatures().webAnimationsCSSIntegrationEnabled())
        ASSERT(!frame().animation().hasAnimations());

Doesn't seem related to the audio session category change; it may have some strange interaction with modern media controls (as maybe they rely on web animation).