✅ fix flaky test #4168
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✅ fix flaky test #4168
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`viewportObservable.spec.ts` changes the page to add scrollbars, causing some asynchronous events to be fired *after* the test has completed. If `recorder.spec.ts` is executed just after, its test might fail because it'll record those asynchronous events. This is the same issue we had with `scroll.spec.ts`. In the past, we tried to be smart and predict which events will be triggered, and wait for them. But it's a bit complex and not reliable on every browsers. This commit simplifies this workaround by waiting for two frames. When scrolling/changing viewport, the browser will first paint it, and then emit events. The second frame should reliably come after events are emitted (tested in Chrome, Firefox and Safari). Reproduce flaky test: git checkout 56a15f1 yarn test:unit --seed 26598
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✅ Tests 🎉 All green!❄️ No new flaky tests detected 🎯 Code Coverage 🔗 Commit SHA: 14258e6 | Docs | Datadog PR Page | Was this helpful? Give us feedback! |
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BeltranBulbarellaDD
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Feb 12, 2026
thomas-lebeau
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Feb 12, 2026
| @@ -1,9 +1,13 @@ | |||
| const cleanupTasks: Array<() => void> = [] | |||
| type CleanupTask = () => unknown | |||
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🥜 nitpick:
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| type CleanupTask = () => unknown | |
| type CleanupTask = () => void | Promise<void> |
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That was my initial thought, but then it lead to a typechecking issue https://gitlab.ddbuild.io/DataDog/browser-sdk/-/jobs/1420187767
Sooo... I just used unknown because we don't really care of the result?
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Motivation
viewportObservable.spec.tschanges the page to add scrollbars, causing some asynchronous events to be fired after the test has completed. Ifrecorder.spec.tsis executed just after, its test might fail because it'll record those asynchronous events.This is the same issue we had with
scroll.spec.ts. In the past, we tried to be smart and predict which events will be triggered, and wait for them. But it's a bit complex and not reliable on every browsers.Changes
This commit simplifies this workaround by waiting for two frames. When scrolling/changing viewport, the browser will first paint it, and then emit events. The second frame should reliably come after events are emitted (tested in Chrome, Firefox and Safari).
Test instructions
Reproduce flaky test:
Confirm that it's gone when running the tests with the same seed after applying this PR changes
Checklist