poll a slow-updating backend value inside a playwright assertion using expect.poll instead of a manual retry loop
domain: playwright.dev · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
wrap the value-producing call (e.g. an API request or DB check) in an async function passed to expect.poll(async () => { ... })
chain a standard matcher such as .toBe(200) or .toEqual(expected) onto the poll call to define the success condition
optionally pass { timeout: ms } and a custom message as the second argument to expect.poll to control how long polling continues and improve failure output
run the test and confirm Playwright retries the function on the built-in interval schedule (default roughly 100/250/500/1000ms) until the matcher passes or the timeout elapses
combine with expect.soft(...).poll(...) if the assertion should not immediately abort the test on failure
Known gotchas
expect.poll re-invokes the entire callback function on each interval, so it must be idempotent and side-effect-safe to call repeatedly
the default poll timeout is much shorter than a full test timeout, so long-running eventual-consistency checks need an explicit timeout override
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