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Sarj Standards

TypeScript · testing

no-sleep-in-test-body

eslint:no-sleep-in-test-body

Disallow a fixed timed sleep directly in a test body; it flakes under CI load. Synchronize on the signal or use fake timers.

Default
error
Fix
none
Languages
typescript

Why

Wall-clock delays make test correctness depend on scheduler and machine speed.

Fix

Await the observable signal or advance deterministic fake timers.

Before / after

Executed by this rule’s unit tests.

Before

Do not wait for wall-clock time

src/retry.test.ts · focus
it('retries', async () => { await sleep(50); expect(done()).toBe(true); });

After

Advance time deterministically

src/retry.test.ts · focus
it('retries', async () => { vi.useFakeTimers(); const result = retry(); await vi.advanceTimersByTimeAsync(50); await result; });

Limits

  • Only fixed nonzero sleeps directly inside test and per-test hook callbacks are checked; nested fakes and parameterized delays are excluded.

Files

**/*.test.***/*.spec.***/tests/****/__tests__/**

Message IDs

noSleepInTestBody