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test(cloudflare): Prevent spurious unhandled rejection in integration test runner - #21545
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andreiborza merged 1 commit intoJun 15, 2026
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… test runner Fixes#21202 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Fixes the recurring "Unhandled error" flake in the Cloudflare Integration Tests job (auto-reported flaky test). The failing "test" is not a real test case — it is Vitest's synthetic Unhandled Error report, raised when an unhandled promise rejection occurs anywhere during the test file run, and then surfaced by the flaky-test bot as a test named "Unhandled error".
Root cause
In
dev-packages/cloudflare-integration-tests/runner.ts, the completion promiseisCompleteis rejected viareject(...)from several background event handlers that fire at arbitrary times relative to the test'sawaitpoints:child.on('error', onChildError)/childSubWorker.on('error', onChildError)childSubWorker.on('exit', ...)(treats every sub-worker exit — including the kill during teardown — as an error)newEnvelopecallback (on an envelope mismatch / late envelope)When one of these fires while nothing is currently awaiting
isComplete(e.g. a wrangler sub-worker transiently exits while the test is parked inmakeRequest, or a stray event arrives after the test has moved on), the rejection has no attached handler. Node then emitsunhandledRejection, Vitest reports it as an Unhandled Error, and the whole suite fails. The timing dependence on child-process / network events is exactly what makes it flaky.Fix
Attach a no-op rejection handler to
isCompleteup-front so background rejections can never surface as unhandled. The real rejection is still delivered to callers throughcompleted()(which returns the same promise), so genuine failures continue to fail the test — no assertions or coverage are weakened. The change is confined to the test harness.Fixes#21202