Excited to announce that I've officially joined @chromatic.com! My main focus will be working around features related to @vitest.dev 🤝

I'd like to avoid forking Istanbuljs monorepo just for Vitest. Any istanbuljs Github organization members here who could make me a maintainer there? (@kentcdodds.com, @jasonkurian.dev 👋) github.com/vitest-dev/v...

Vitest hit 20 million weekly downloads in December, right before Christmas break. To put that into context: 5 million @vitest.dev weekly downloads were reached in June 2024, meaning a 4x increase in just 1.5 years. 🎉

When using vite@8-beta with Vitest users no longer need to add magical '@preserve' keywords in their coverage ignore hints. Originally this work-around was needed due to esbuild's (intentional) lack of support for comment preserving. Oxc has built-in support for JS coverage tools' ignore hints.

Vitest 4.0.11 adds an experimental `fsModuleCache` flag to cache module transforms between reruns. Learn more: vitest.dev/config/exper... This is an opt-in feature, please let us know how it works for you! And example of a single test file that imports a lot of files (~1500). Almost a 50% boost!

⚡ ever wanted to download @stackblitz.com projects without opening the site? you now can 🎉 🌐 web: replace stackblitz.com w/ stackblitz.zip in any edit url 🖥️ cli: `npx stackblitz-zip <url>` or `npx stackblitz-clone <url>` 📦 npm: `npm i stackblitz-zip` built for myself to grab repros from issues

Excited to see Typesafe CSF factories solve RFC I wrote two years ago. No more explicit TS typings! github.com/storybookjs/...

My talk slides are available here hiroshi-talks.vercel.app/2025-10-25/1 also with source code in github.com/hi-ogawa/talks It was a great experience to talk with many awesome folks in person! Thanks @vuefes.bsky.social for the opportunity!

Vitest 4 is out! - Browser Mode is Stable - Visual Regression Testing - Improved Debugging - Pool Stabilization - New APIs - Bug Fixes Stay updated with our blog post: vitest.dev/blog/vitest-4

After maintaining Tinypool for over 2 years I'm happy to see next version of Vitest dropping it. I've written some reasoning about this in the linked PR. Even though this change is significant for Vitest, I'm more confident about it than making new changes in Tinypool. github.com/vitest-dev/v...

VoidZero's @erus.dev talks about the upcoming @vitest.dev features including the new report API and multi-browser configuration as well as what to expect in Vitest 4 🧪 Full video in comments

Watch VoidZero’s @overlookmotel.bsky.social explain how oxlint tackles JS-Rust interoperability to maintain high performance for plugins. Full video in comment 👇

Setting custom `process.title` in Node takes around 10-20ms. Vitest used to do this for every isolated test file so that debugging test runner processes was a bit nicer experience. But it's not worth the performance hit.

Published a post I started writing half a year ago. Make sure to use the latest versions of each build tools and configure the settings appropriately! green.sapphi.red/blog/address...

Our latest post walks through how to use the coverage reporting in Storybook 9 to be sure your components are well-tested.

We've added new coverage provider comparison page on Vitest documentation. This guide describes the lower level differences between Istanbul and V8. It should help users choosing which provider to use. vitest.dev/guide/covera...

AST based V8 code coverage is finally here! I thought of this feature first time over 2 years ago, but knew it would require so much work that I couldn't finish it by working on Vitest just on weekends. Ever since @stackblitz.com hired me to work on Vitest I knew I could finish features like this.

Vitest 3.2 is out! - New Annotations API - Scoped Fixtures - Custom Browser Locators API - Test Signal - Better V8 Coverage Result And many more features! vitest.dev/blog/vitest-...

Onboarding on new @storybook.js.org projects is just perfect. So nice to have testing setup *covered* out-of-the-box. 🤝

@bolt.new are looking for an engineer to advance web computing by working on WebContainer, the first in-browser WebAssembly-based operating system. You'd be getting paid to be an Open Source contributor, AND you'd get to work with @patak.dev. Sounds pretty good to us! opensourcepledge.com/jobs/

Tinypool is now built with tsdown! Migration from tsup was smooth and required minimal changes. Thanks to @sxzz.dev 💯

After couple of days looking at *.cpuprofile's, I think it's getting closer to stable v1 release. The ~3MB checker.ts from Typescript repo is perfect benchmarking reference for tools that process source code. When generating coverage for 'vuejs/core' repo, speed is close to original v8-to-istanbul.

This release includes long-awaited "--silent=passed-only" option, that can be used to hide console.log calls from passing tests. Only the logs from failing tests are reported.

Finalizing rewrite of AST-aware v8-to-istanbul. This will provide accuracy of Istanbul coverage for V8 coverage reports. I've intentionally kept this tool unopinionated so that it's not strictly tied to just @vitest.dev - it should be usable with Jest, C8, Playwright and node:test too.

We are proud to announce the First Ever ViteConf taking place in person 🤩 Join the Creator of Vite, @evanyou.me, Core Team, Ecosystem Authors and Experts! 📍 10 October, Amsterdam 👋 Sign up for the waiting list to be notified about the ticket release via viteconf.org

Huge improvement for Vitest development workflow, thanks to isolated declaration! I didn't think the migration was possible until I see PRs by @sxzz.dev. Just started to sponsor Kevin for the amazing work!

Tree-view of @vitest.dev verbose reporter is coming back! We (well I did) forgot to implement this during v3's reporter rewrites. I had already forgot how good it looks.

In 2025, we’re doubling down on our support to Open Source. We’re thrilled to announce the Bolt 100K Open Source Fund:

🤏 it's a good day for tinypool! thank you so much @sebastienlorber.com and @ariperkkio.dev ❤️ github.com/facebook/doc...

Huge thanks to @sapphi.red for helping the @vitest.dev team with these findings. Perfect collaboration between projects. 🤝

I finally met @ariperkkio.dev! And he got his first edition vitest shirt, that has been waiting for him for a year at home

everything is better with open source friends

Installing dependencies while coding offline in an airplane. The --prefer-offline from @pnpm.io is just perfect. 🤩

Expressing appreciation for ‪the work of @ariperkkio.dev‬ and the other @vitest.dev devs. The absolute smoothness of Vitest 3.0's terminal reporter is something I didn't even realize I needed.

Today we're announcing $105.5m in funding to take Bolt to new heights! 🚀 Our Series B was led by Emergence & GV, with participation from Madrona, The Chainsmokers (Mantis), Conviction, and some of the best operators building in devtools & AI

we've now migrated parse5 to use @vitest.dev 🎉 big thanks to @ariperkkio.dev for help along the way too

I love the @vitest.dev v3's new reporter! The team is doing incredible work! 💛🔥

Smooth terminal reporters, new Node APIs, new Reporter APIs, inline Workspaces and much more! So happy to see all these features finally out. I think this was the most demanding major release so far. 🥳

Working on the new @vitest.dev reporter API gif by @ariperkkio.dev

🚀 Thrilled to announce my interactive #WebAssembly course! Learn WebAssembly from the ground up with: 🔍 Custom-built debugger & VM 📊 Live stack & memory insights 💻 Hands-on exercises 🛠️ Build real projects Level up with WebAssembly! ✨ 👉 learn-wasm.dev

We've opened a new tinylibs discord! This should help give us a space to collab more on feedback and new libraries discord.gg/TwSXGv6rqM

This kind of growth just amazes me. On 12/2023 Vitest had 3M weekly downloads. Now in 12/2024 there's almost 8M. Maybe we can share #2 with Storybook next year! 📈 2024.stateofjs.com/en-US/librar...

The beta has started!

If you like what we are doing on bolt.new, we are hiring. I'd love to talk to you. If you're interested, feel free to send me a DM.

⚡️ Yes! Vitest is generally faster than Jest -- but is feedback speed the only factor that matters? If you are still on the fence about switching to Vitest, here are 15+ reasons that will convince you! 📝 cookbook.marmicode.io/angular/why-... #javascript #angular #testing

pnpm create tutorial

@pkg.pr.new is a huge fan of @ariperkkio.dev 💙

Released in 2.2.0-beta.2 and it's even smoother now! Here's comparison of latest Vitest on left vs beta on right. Flickering is gone and now you can scroll up to see results without scroll jumping. And of course there's the status summary of active test run on the bottom. github.com/vitest-dev/v...

TutorialKit v1.3.0 is now out! 🥳 You can now omit part and chapter levels if your tutorial doesn't need that deeply nested architecture! There is also new 'downloadAsZip' option that adds button for downloading whole lesson as .zip-file with a single click. Release notes: github.com/stackblitz/t....

Case study on a Remix and Vite app from AnthropicAI