fix: advance fake timers with expect.poll interval (#10022)

hi-ogawa · claude · web-flow · commit 3f5bfa3658e3 · 2026-03-30T10:27:48.000+02:00
Co-authored-by: Claude Sonnet 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/packages/vitest/src/integrations/chai/poll.ts b/packages/vitest/src/integrations/chai/poll.ts
@@ -3,6 +3,7 @@ import type { Test } from '@vitest/runner'
 import { chai } from '@vitest/expect'
 import { delay, getSafeTimers } from '@vitest/utils/timers'
 import { getWorkerState } from '../../runtime/utils'
+import { vi } from '../vi'
 
 // these matchers are not supported because they don't make sense with poll
 const unsupported = [
@@ -123,6 +124,9 @@ export function createExpectPoll(expect: ExpectStatic): ExpectStatic['poll'] {
                   }
 
                   await delay(interval, setTimeout)
+                  if (vi.isFakeTimers()) {
+                    vi.advanceTimersByTime(interval)
+                  }
                 }
               }
             }
diff --git a/test/core/test/expect-poll.test.ts b/test/core/test/expect-poll.test.ts
@@ -66,6 +66,21 @@ test('fake timers don\'t break it', async () => {
   expect(diff >= 100).toBe(true)
 })
 
+test('fake timers are advanced on each poll interval', async ({ onTestFinished }) => {
+  vi.useFakeTimers()
+  onTestFinished(() => {
+    vi.useRealTimers()
+  })
+
+  let didAdvance = false
+
+  setTimeout(() => {
+    didAdvance = true
+  }, 50)
+
+  await expect.poll(() => didAdvance, { interval: 100 }).toBe(true)
+})
+
 test('custom matcher works correctly', async () => {
   const fn = vi.fn()
   let idx = 0

Original file line number	Diff line number	Diff line change
`@@ -3,6 +3,7 @@ import type { Test } from '@vitest/runner'`
`3`	`3`	`import { chai } from '@vitest/expect'`
`4`	`4`	`import { delay, getSafeTimers } from '@vitest/utils/timers'`
`5`	`5`	`import { getWorkerState } from '../../runtime/utils'`
	`6`	`+import { vi } from '../vi'`
`6`	`7`
`7`	`8`	`// these matchers are not supported because they don't make sense with poll`
`8`	`9`	`const unsupported = [`
`@@ -123,6 +124,9 @@ export function createExpectPoll(expect: ExpectStatic): ExpectStatic['poll'] {`
`123`	`124`	`}`
`124`	`125`
`125`	`126`	`await delay(interval, setTimeout)`
	`127`	`+ if (vi.isFakeTimers()) {`
	`128`	`+ vi.advanceTimersByTime(interval)`
	`129`	`+ }`
`126`	`130`	`}`
`127`	`131`	`}`
`128`	`132`	`}`