test(desktop): deflake mid-scroll older-history spinner smoke test#1632
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The "older-history spinner stays visible in viewport while fetching mid-scroll" smoke test drove the timeline with three mouse.wheel gestures and fixed 100ms sleeps, then asserted scrollTop > 8. Wheel delta handling varies across CI runners, so the final net position sometimes landed at scrollTop 0 — failing the assertion on all retries and intermittently breaking main (e.g. runs 28915175821, 28891719863) with no related code change. Replace the wheel choreography with direct scrollTop writes: park at 150 to trigger the older fetch, wait for the spinner, then jump one viewport down while the fetch is still in flight. Deterministic mid-scroll position, same assertion targets (spinner visible + pinned within the viewport away from the top). Verified locally: 10/10 repeats pass; full scroll-history smoke suite passes. Co-authored-by: Pinky <44b8e82baa6e0e254e0208d68f335c283c94e7b78dd1fa10d5a49d3f13dd0435@sprout-oss.stage.blox.sqprod.co> Signed-off-by: Wes <wesbillman@users.noreply.github.com>
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Why
mainCI is intermittently red on Desktop Smoke E2E (4): thescroll-history.spec.tstest "older-history spinner stays visible in viewport while fetching mid-scroll" failsexpect(scrollTop).toBeGreaterThan(8)with0on all 3 retries (runs 28915175821, 28891719863). The test file hadn't changed since #1533 and the failing commits didn't touch scroll code — it's test flake, not a product regression.What
The test drove the timeline with three
mouse.wheelgestures separated by fixed 100ms sleeps, then asserted the timeline ended up mid-scroll. Wheel delta handling varies across CI environments, so the net position sometimes landed atscrollTop 0— the one position the test must avoid.Replaced the wheel choreography with deterministic
scrollTopwrites:scrollTop = 150to trigger the older-history fetch (same pattern the sibling "never overlap" test uses),Same assertion targets as before — only the flaky input choreography changed.
Verification
--repeat-each=10on the target test: 10/10 passscroll-history.spec.tssmoke suite: 15/15 passpnpm typecheck,pnpm lint,pnpm check: clean(Note: two other recent red runs on main were runner-infra apt failures installing Playwright deps —
packages.microsoft.comclearsign errors — self-healing, not addressable in-repo.)