Support Vitest 4 in `@cloudflare/vitest-pool-workers` by penalosa · Pull Request #11632 · cloudflare/workers-sdk

penalosa · 2025-12-12T23:20:26Z

Fixes #11064
Fixes #10260 (tests added to verify the mentioned libraries can be imported)
Fixes #9957 (provide data moved from HTTP headers to WebSocket messages, removing the ~8 KB size limit)
Fixes #8369 (defineWorkersConfig is removed)
Fixes #7795 (everything is now encapsulated in a plugin, and so this type of configuration problem is impossible)
Fixes #7717 (leaked FSWatcher from Pages ASSETS binding is now closed via AbortSignal on pool worker stop)
Fixes #7339 (we no longer recommend importing env from cloudflare:test. Instead, import env from cloudflare:workers and use withEnv to override the value: https://developers.cloudflare.com/workers/runtime-apis/bindings/#overriding-env-values)
Fixes #7324 (nodejs_compat_v2 and Node module flags are now forcibly enabled during tests)
Fixes #7288 (new WorkersSnapshotEnvironment proxies snapshot file operations over a service binding)
Fixes #6465 (workerd resolve condition is explicitly included, node condition is removed)
Fixes #6214 (bare Node.js specifiers like "url" are resolved by prepending node: in the module fallback)
Fixes #5592 (SSR optimizer replaced with server.deps.inline = true, so Stripe resolves to its worker build)
Fixes #5396 (module graph is now populated via standard Vitest PoolWorker RPC — the UI should work)
Fixes #11690, fixes #11031, fixes #7707, fixes #5524 (Per-test isolated storage is completely removed, and so the entire mechanism that caused this is gone)
Fixes #6391 (fetch mock is now removed entirely)

This a breaking change to the @cloudflare/vitest-pool-workers integration in order to support Vitest v4. Along with supporting Vitest v4 (and dropping support for Vitest v2 and v3), we've made a number of changes that may require changes to your tests. Our aim has been to improve stability & the foundations of @cloudflare/vitest-pool-workers as we move towards a v1 release of the package.

We've made a codemod to make the migration easier: wrangler codemod vitest-pool-v3-to-v4, which will make the required changes to your config file.

isolatedStorage & singleWorker: These have been removed in favour of a simpler isolation model that more closely matches Vitest. Storage isolation is now on a per test file basis, and you can make your test files share the same storage by using the Vitest flags --max-workers=1 --no-isolate
import { env, SELF } from "cloudflare:test": These have been deprecated in favour of import { env, exports } from "cloudflare:workers". exports.default.fetch() has the same behaviour as SELF.fetch(), except that it doesn't expose Assets. To test your assets, use the env.ASSETS bindings or write an integration test using startDevWorker() (recommended)
import { fetchMock } from "cloudflare:test": This has been removed. Instead, mock globalThis.fetch or use ecosystem libraries like MSW (recommended).

Tests
- Tests included/updated
- Tests not necessary because:
Public documentation
- Cloudflare docs PR(s): Introduce vitest4 to vitest-pool-workers cloudflare-docs#28908
- Documentation not necessary because: coming soon
Wrangler V3 Backport
- Wrangler PR:
- Not necessary because: not Wrangler

A picture of a cute animal (not mandatory, but encouraged)

changeset-bot · 2025-12-12T23:20:31Z

🦋 Changeset detected

Latest commit: 405a192

The changes in this PR will be included in the next version bump.

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

pkg-pr-new · 2025-12-17T22:27:24Z

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@11632

@cloudflare/kv-asset-handler

npm i https://pkg.pr.new/@cloudflare/kv-asset-handler@11632

miniflare

npm i https://pkg.pr.new/miniflare@11632

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@11632

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@11632

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@11632

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@11632

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@11632

wrangler

npm i https://pkg.pr.new/wrangler@11632

commit: e8bf541

fixtures/vitest-pool-workers-examples/ai-vectorize/vitest.config.ts

fixtures/vitest-pool-workers-examples/module-resolution/src/index.ts

packages/vitest-pool-workers/scripts/bundle.mjs

packages/vitest-pool-workers/src/pool/cloudflare-pool-worker.ts

packages/vitest-pool-workers/src/pool/config.ts

packages/vitest-pool-workers/src/shared/chunking-socket.ts

packages/vitest-pool-workers/src/worker/lib/cloudflare/test-runner.ts

claude · 2025-12-18T15:10:27Z

Claude encountered an error —— View job

Reviewing Changesets

Read changeset guidelines
Review .changeset/many-fishes-raise.md
Review .changeset/wrangler-codemod-command.md
Check attached image for cute animals

ascorbic

Mostly some questions. Otherwise, looking great!

packages/vitest-pool-workers/src/pool/cloudflare-pool-worker.ts

packages/vitest-pool-workers/src/pool/plugin.ts

packages/vitest-pool-workers/src/pool/cloudflare-pool-worker.ts

packages/vitest-pool-workers/package.json

packages/vitest-pool-workers/types/cloudflare-test.d.ts

packages/vitest-pool-workers/src/worker/index.ts

packages/wrangler/src/codemod.ts

packages/vitest-pool-workers/src/pool/index.ts

…pport

workers-devprod · 2026-03-05T23:01:27Z

Codeowners approval required for this PR:

✅ @cloudflare/deploy-config
✅ @cloudflare/workflows
✅ @cloudflare/wrangler

Show detailed file reviewers

github-actions · 2026-03-05T23:07:42Z

✅ All changesets look good

…pport

Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

…pport

…tsconfig Use the dynamic env from cloudflare:workers (live ESM binding) instead of the static this.env captured at WorkerEntrypoint construction. This allows withEnv() overrides to propagate through exports.default.fetch() and RPC calls to user handler invocations. Also fix workers-assets root tsconfig to only include ./*.ts, matching the pattern used by all other fixtures. The src/ and test/ subdirectories have their own tsconfigs with the correct workers types.

…pport # Conflicts: # pnpm-lock.yaml

singleWorker was removed from the pool options schema but was still being passed in console.test.ts and inspector.test.ts — silently stripped by Zod validation. Also expand the inline comment for no_handle_cross_request_promise_resolution to explain what it does and why it's needed.

Call worker.fetch() directly inside withEnv() so the overridden env is visible to the handler. exports.default.fetch() goes through service binding dispatch which creates a new request context — needs runtime team input on whether withEnv() should propagate across that boundary.

workers-devprod added this to workers-sdk Dec 12, 2025

github-project-automation bot moved this to Untriaged in workers-sdk Dec 12, 2025

penalosa force-pushed the penalosa/vitest-v4-support branch 4 times, most recently from 107ac9f to e018115 Compare December 17, 2025 22:22

penalosa commented Dec 17, 2025

View reviewed changes

penalosa force-pushed the penalosa/vitest-v4-support branch from e28ec0a to d45260d Compare December 18, 2025 15:10

penalosa force-pushed the penalosa/vitest-v4-support branch from d45260d to 60332b7 Compare December 18, 2025 17:58

penalosa added 3 commits December 18, 2025 19:06

Support Vitest v4

f649413

fix build

3afc4f6

fix build

964012e

penalosa force-pushed the penalosa/vitest-v4-support branch from b4ce401 to 964012e Compare December 18, 2025 19:24

penalosa added 3 commits December 18, 2025 20:09

fix build

e1f2a8b

fix snapshot

cfc5f70

fix fixture tests

704466b

penalosa marked this pull request as ready for review December 18, 2025 21:47

penalosa requested review from a team as code owners December 18, 2025 21:47

ascorbic reviewed Dec 19, 2025

View reviewed changes

penalosa added 6 commits December 19, 2025 18:20

env & exports

99a88c9

better module runner

3e60beb

Merge remote-tracking branch 'origin/main' into penalosa/vitest-v4-su…

9dec2c5

…pport

fix tests after merge

3037a20

green

c6af16d

run with vitest3

64982d4

Merge remote-tracking branch 'origin/main' into penalosa/vitest-v4-su…

343ffb9

…pport

penalosa force-pushed the penalosa/vitest-v4-support branch from f44feba to 343ffb9 Compare March 5, 2026 23:55

Update fixtures/get-platform-proxy/tests/get-platform-proxy.env.test.ts

2eeb830

Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

This comment was marked as resolved.

Sign in to view

fix check

6de6838

taylorlee approved these changes Mar 6, 2026

View reviewed changes

fix: resolve CI failures from NodeJS namespace and stale snapshot

9a224e4

pombosilva approved these changes Mar 6, 2026

View reviewed changes

penalosa added 2 commits March 9, 2026 11:49

Merge remote-tracking branch 'origin/main' into penalosa/vitest-v4-su…

04f0bf5

…pport

Fix CI: codemods type mismatch and format-errors mock for vitest v4

55a5510

This comment was marked as resolved.

Sign in to view

penalosa added 5 commits March 9, 2026 17:56

Add config API migration example to changeset

4b70c1e

Merge remote-tracking branch 'origin/main' into penalosa/vitest-v4-su…

1d0e89f

…pport # Conflicts: # pnpm-lock.yaml

This comment was marked as resolved.

Sign in to view

Merge branch 'main' into penalosa/vitest-v4-support

405a192

penalosa merged commit a6ddbdb into main Mar 10, 2026
68 of 74 checks passed

penalosa deleted the penalosa/vitest-v4-support branch March 10, 2026 21:26

github-project-automation bot moved this from Approved to Done in workers-sdk Mar 10, 2026

workers-devprod mentioned this pull request Mar 10, 2026

Version Packages #12840

Merged

edmundhung mentioned this pull request Mar 12, 2026

fix(vitest-pool-workers): update peer dependency for vitest to 4.1 #12867

Merged

5 tasks

This was referenced Mar 19, 2026

Support for vitest bench in @cloudflare/vitest-pool-workers/config #10049

Closed

Ensure wider compatibility with npm ecosystem #5382

Closed

Vitest significantly slower after fix of #6844 #9029

Closed

fhanau mentioned this pull request Mar 24, 2026

Add support for connect handler in vitest and vite tests #12802

Open

5 tasks

penalosa mentioned this pull request Mar 26, 2026

[vitest-pool-workers] Add regression tests for onUnhandledError callback #13076

Open

5 tasks

Conversation

penalosa commented Dec 12, 2025 • edited by lrapoport-cf Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

changeset-bot bot commented Dec 12, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🦋 Changeset detected

Uh oh!

pkg-pr-new bot commented Dec 17, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

claude bot commented Dec 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Reviewing Changesets

Uh oh!

ascorbic left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

workers-devprod commented Mar 5, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

github-actions bot commented Mar 5, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

This comment was marked as resolved.

Uh oh!

This comment was marked as resolved.

Uh oh!

This comment was marked as resolved.

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

12 participants

penalosa commented Dec 12, 2025 •

edited by lrapoport-cf

Loading

changeset-bot bot commented Dec 12, 2025 •

edited

Loading

pkg-pr-new bot commented Dec 17, 2025 •

edited

Loading

claude bot commented Dec 18, 2025 •

edited

Loading

ascorbic left a comment •

edited

Loading

workers-devprod commented Mar 5, 2026 •

edited

Loading

github-actions bot commented Mar 5, 2026 •

edited

Loading