feat!: update @sinonjs/fake-timers and support mocking Temporal (#10654)

Co-authored-by: Hiroshi Ogawa <4232207+hi-ogawa@users.noreply.github.com>
Co-authored-by: OpenCode (claude-opus-4-8) <noreply@opencode.ai>

Author: hi-ogawa

docs/config/faketimers.md

@@ -18,7 +18,7 @@ Installs fake timers with the specified Unix epoch.
 
 ## fakeTimers.toFake
 
-- **Type:** `('setTimeout' | 'clearTimeout' | 'setImmediate' | 'clearImmediate' | 'setInterval' | 'clearInterval' | 'Date' | 'nextTick' | 'hrtime' | 'requestAnimationFrame' | 'cancelAnimationFrame' | 'requestIdleCallback' | 'cancelIdleCallback' | 'performance' | 'queueMicrotask')[]`
+- **Type:** `('setTimeout' | 'clearTimeout' | 'setImmediate' | 'clearImmediate' | 'setInterval' | 'clearInterval' | 'Date' | 'nextTick' | 'hrtime' | 'requestAnimationFrame' | 'cancelAnimationFrame' | 'requestIdleCallback' | 'cancelIdleCallback' | 'performance' | 'queueMicrotask' | 'Intl' | 'Temporal')[]`
 - **Default:** everything available globally except `nextTick` and `queueMicrotask`
 
 An array with names of global methods and APIs to fake. For example, to only mock `setTimeout()` and `nextTick()`, specify this property as `['setTimeout', 'nextTick']`.
@@ -27,7 +27,7 @@ Mocking `nextTick` is not supported when running Vitest inside `node:child_proce
 
 ## fakeTimers.toNotFake
 
-- **Type:** `('setTimeout' | 'clearTimeout' | 'setImmediate' | 'clearImmediate' | 'setInterval' | 'clearInterval' | 'Date' | 'nextTick' | 'hrtime' | 'requestAnimationFrame' | 'cancelAnimationFrame' | 'requestIdleCallback' | 'cancelIdleCallback' | 'performance' | 'queueMicrotask')[]`
+- **Type:** `('setTimeout' | 'clearTimeout' | 'setImmediate' | 'clearImmediate' | 'setInterval' | 'clearInterval' | 'Date' | 'nextTick' | 'hrtime' | 'requestAnimationFrame' | 'cancelAnimationFrame' | 'requestIdleCallback' | 'cancelIdleCallback' | 'performance' | 'queueMicrotask' | 'Intl' | 'Temporal')[]`
 - **Default:** `[]`
 
 An array with names of global methods and APIs to keep native. All other available timers will be mocked. For example, to keep `setInterval()` native and mock all other timers, specify this property as `['setInterval']`.

docs/guide/migration.md

@@ -52,6 +52,24 @@ vitest --ui
 # UI started at http://localhost:51204/__vitest__/?token=...
 ```
 
+### Fake Timers Now Mock `Temporal`
+
+Vitest now mocks the [`Temporal`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal) API alongside `Date` when fake timers are enabled, following the [`@sinonjs/fake-timers` v15.4 update](https://github.com/sinonjs/fake-timers/blob/main/CHANGELOG.md#1540--2026-05-05). This only takes effect when `Temporal` is available on the global object — either natively (Node.js >= 26 by default, behind `--harmony-temporal` on older versions, and supporting browsers) or through a globally installed polyfill such as `import 'temporal-polyfill/global'`.
+
+Previously `Temporal.Now` kept returning the real wall-clock time even when [`vi.useFakeTimers()`](/api/vi#vi-usefaketimers) was active. Now it follows the mocked clock:
+
+```ts
+vi.useFakeTimers({ now: 0 })
+
+Temporal.Now.instant().epochMilliseconds // 0 (was the real time in v4)
+```
+
+`Temporal` is part of the default set of faked APIs, so it is controlled by [`fakeTimers.toFake`](/config/#faketimers-tofake) and [`fakeTimers.toNotFake`](/config/#faketimers-tonotfake). To keep `Temporal` native, add it to `toNotFake`:
+
+```ts
+vi.useFakeTimers({ toNotFake: ['Temporal'] })
+```
+
 ### Removed `test.sequential`, `describe.sequential`, and `sequential` Options
 
 Vitest 5.0 removes the deprecated `test.sequential`, `describe.sequential`, and `sequential` test options. Use `concurrent: false` when you need a test or suite to opt out of inherited or globally configured concurrency.

packages/vitest/package.json

@@ -192,7 +192,7 @@
     "@edge-runtime/vm": "^5.0.0",
     "@jridgewell/trace-mapping": "catalog:",
     "@opentelemetry/api": "^1.9.0",
-    "@sinonjs/fake-timers": "15.3.2",
+    "@sinonjs/fake-timers": "15.4.0",
     "@types/estree": "catalog:",
     "@types/istanbul-lib-coverage": "catalog:",
     "@types/istanbul-reports": "catalog:",

…tches/@sinonjs__fake-timers@15.3.2.patch …tches/@sinonjs__fake-timers@15.4.0.patchpatches/@sinonjs__fake-timers@15.3.2.patch renamed to patches/@sinonjs__fake-timers@15.4.0.patch patches/@sinonjs__fake-timers@15.3.2.patch renamed to patches/@sinonjs__fake-timers@15.4.0.patch

@@ -1,5 +1,5 @@
 diff --git a/src/fake-timers-src.js b/src/fake-timers-src.js
-index 7d4cfa1b6b8aebc8575e08bd432f8f8ca43d3c4f..09d12bec356aa1048f09771e915075fdecb065b9 100644
+index 241a7ad3eeb8b5eb691439fab31a87ef13c76345..2df1b2086670bfa06cdb148a9dbe61cd41680f2e 100644
 --- a/src/fake-timers-src.js
 +++ b/src/fake-timers-src.js
 @@ -2,14 +2,14 @@
@@ -20,7 +20,7 @@ index 7d4cfa1b6b8aebc8575e08bd432f8f8ca43d3c4f..09d12bec356aa1048f09771e915075fd
      } catch {
          // ignored
      }
-@@ -510,7 +510,7 @@ function withGlobal(_global) {
+@@ -537,7 +537,7 @@ function withGlobal(_global) {
          isPresent.hrtime && typeof _global.process.hrtime.bigint === "function";
      isPresent.nextTick =
          _global.process && typeof _global.process.nextTick === "function";

pnpm-lock.yaml

@@ -39,7 +39,7 @@ overrides:
   vite: 'catalog:'
   vitest: workspace:*
 patchedDependencies:
-  '@sinonjs/fake-timers@15.3.2': patches/@sinonjs__fake-timers@15.3.2.patch
+  '@sinonjs/fake-timers@15.4.0': patches/@sinonjs__fake-timers@15.4.0.patch
   acorn@8.11.3: patches/acorn@8.11.3.patch
   cac@6.7.14: patches/cac@6.7.14.patch
   istanbul-lib-instrument: patches/istanbul-lib-instrument.patch
@@ -87,7 +87,7 @@ catalog:
   playwright: ^1.61.0
   rollup: ^4.59.0
   semver: ^7.8.3
-  sinon: ^21.0.3
+  sinon: ^22.0.0
   sinon-chai: ^4.0.1
   sirv: ^3.0.2
   std-env: ^4.0.0-rc.1

pnpm-workspace.yaml

@@ -0,0 +1,26 @@
+import { afterEach, expect, it, vi } from 'vitest'
+
+// use polyfill for node < 26
+if (!globalThis.Temporal) {
+  await import('temporal-polyfill/global')
+}
+
+afterEach(() => {
+  vi.useRealTimers()
+})
+
+it('Temporal.Now follows fake timers', () => {
+  const real = globalThis.Temporal
+
+  vi.useFakeTimers({ now: 0 })
+  expect(globalThis.Temporal).not.toBe(real)
+  expect(globalThis.Temporal.Now.instant().epochMilliseconds).toBe(0)
+
+  vi.advanceTimersByTime(1234)
+  expect(globalThis.Temporal.Now.instant().epochMilliseconds).toBe(1234)
+
+  // restore
+  vi.useRealTimers()
+  expect(globalThis.Temporal).toBe(real)
+  expect(globalThis.Temporal.Now.instant().epochMilliseconds).not.toBe(1234)
+})