Vitest

Vitest 5 is here! 🎉 - Big performance improvements (vm pools up to 53% faster, ~18% boost across the board including Browser Mode) - New builtin Trace View in Browser Mode - Nested projects support - New benchmarking API - New `vi.when` API - Better defaults - And a lot of bug fixes!

Latest work on Vitest's istanbuljs fork removed Babel from coverage-istanbul. Instrumentation is now done with packages that Vitest dep graphs already have: magic-string and rolldown, similar to Vite's own SSR transform. Surprisingly this dep trim improved instrumentation speed 5-10x.

And we are LIVE! Welcome to @viteconf.org 🎉 Join at viteconf.org/live if you dont watch already!

One of the new @vitest.dev 5 features helps you make your tests run faster without trying all config combinations! Learn more from @vladimir.berlin on that and other new goodies in "Why you should migrate to Vitest 5" ✅️ @viteconf.org 2026, Thu 15 Oct, 14:00 UTC. Free and online. viteconf.org

The @vitest.dev ecosystem keeps growing: 19 new packages added to Awesome Vitest last month. The most interesting part of maintaining the list is seeing how the range of tooling has expanded over time. I’ve reorganized the list to better reflect that:

Three days to @ViteConf.org ⚡ Are you hyped? ◆ 30 speakers from the ecosystem ◆ Watch the people behind your favorite tools and frameworks ◆ Fully free and online 📅 October 15 · Starts at 14:00 UTC viteconf.org Building together. We are Vite.

Our Tales from the Void September 2026 Recap is out! 🌌 ⚡ Vite+ 1.0 is out (free & OSS) 🧪 @vitest.dev 5, up to 50% faster ⏬️ @rolldown.rs can now reduce your number of chunks even more 📦 Updates on Bundled Dev Mode now runs the full @vite.dev playground suite 🎤 Less than 10 days to @viteconf.org

Vite+ 1.0 is here 🚀 A single `vp` CLI for managing your Node.js runtime, package manager, and frontend toolchain. Built on top of Vite, Vitest, Rolldown, Oxc, and tsdown. All with a single config. Free and open source under the MIT license. Start with `vp create` or migrate with `vp migrate`.

This Thursday we'll be discussing about Visual Regression Testing using @vitest.dev and @chromatic.com. Join me and @kylegach.com to hear how you can get VRT that's stable across your whole team, not just on your local machine. 📸

@vitest.dev already renders your components in a real browser. Now you can visually test them there, with no test code changes. 🎙️ @ariperkkio.dev, the Vitest core maintainer who built our new plugin, is doing a live walkthru with @kylegach.com to show you how. 🎟️ Save your spot 👇

Last night in Amsterdam and it looks like I'll be heading to the @vitest.dev / @npmx.dev gathering! guild.host/events/vites...

If you are in Amsterdam this Thursday, come to the @vitest.dev x @npmx.dev meetup! guild.host/events/vites...

🚀 Vitest 5.0.1 is out with more than 18 fixes Among them: `define` values are no longer double-quoted in browser mode! It also includes a focused Trace View layout which is used by the Vitest VS Code extension. Time to update 👀 github.com/vitest-dev/v...

Big win! Migrated the whole @netlify.com build repo to @vitest.dev 🎉🎉 Also made heavy use of my snapshot diff tool since ava has binary snapshots (accounting for most of the 40k+ PR 😅)

I’m gonna be honest my life is so much happier with Vitest in it.

Chromatic for @vitest.dev Browser Mode is live. 🧪📸 Browser Mode runs your component tests in a real browser. Now Chromatic checks how those components look by capturing the rendered UI. No new screenshot assertions. No second suite to maintain. 🧵 (1/4)

The @vitest.dev v5 rc is very exciting, performance is great, and all of my wishes are fulfilled ❤️ Trace view is such a killer feature, I'm so happy I didn't have to wait for the stable release to use it.

The @vitest/istanbuljs fork is now ready and will ship in the next version of Vitest. Compared to the original istanbuljs packages it's ESM-only, ships its own typings, drops unnecessary runtime deps, and moves Node 8→22, Babel 7→8 (lib-instrument), React→Preact (html-spa reporter), and more!

bit of a niche thing but i put a tool together for diffing ava and vitest snapshots. migrating from ava to vitest is a pain because: - vitest snapshots are text - ava snapshots are encoded values, cbor'd, then gzipped this tool lets you confirm your new vitest snapshots match the old ones

TIL when running Vitest browser mode (or plain Playwright) on Github Actions on Ubuntu, you can skip the slow "playwright install chromium" step completely by providing channel option. This makes Playwright use the pre-installed Chrome. So many projects out there that could speed their CIs with this

@vitest.dev 5-beta.7 is out with a lot of performance improvements depending on your setup. If you are using jsdom, consider switching to vmThreads pool for x4 speedup! Are your tests now running faster? github.com/vitest-dev/v...

Vitest is now mirrored to @tangled.org! Powered by @danielroe.dev's synchub.to

`vmThreads` is 30% faster in Vitest 5 for your jsdom tests. It is now a much better alternative to the default forks+jsdom. Vitest 5 also comes with a `vitest doctor` command that will find the best settings for you! As a note, browser mode also becomes ~30% faster, but for different reasons :)

How to speed up vitest: De-barrel everything so that the module graph gets smaller. Saves both processing + import time. And get rid of module mocks, which prevents many de-barelling opportunities.

I have cancelled my GitHub Sponsors account today. If you've been sponsoring me before, consider redirecting the funds to Vitest directly 💚

Interested in the story behind @voidzero.dev joining @cloudflare.social? So was I! Luckily @evanyou.me, Founder & CEO of VoidZero, creator of @vuejs.org & @vite.dev, & now part of Cloudflare's #oss team, joined me to discuss. 👉 redmonk.com/videos/evan-... @redmonk.com youtube.com/shorts/98v0t...

Get first access to our @vitest.dev plugin, which adds Chromatic’s visual testing and review to your browser tests. It’s built by @ariperkkio.dev, a Vitest core maintainer. It’s free to use while in beta and requires no changes to your test files. Read on for more info 🧵

🌌 Tales from the Void: Our May 2026 Recap Don't miss out on the news: 🧡 VoidZero is now part of Cloudflare ⚡ Rolldown got its first stable release 🔒 Vite security patches 🧪 Vitest going engine-agnostic 🦀 Oxfmt up to 25% faster 👀 and more from the community Full recap 👇 voidzero.dev/posts/whats-...

VoidZero, the team behind Vite, Vitest, Rolldown, Oxc, and Vite+, is joining Cloudflare. Vite stays open source, vendor-agnostic, and built for everyone. https://cfl.re/4dR0LYA

VoidZero is joining Cloudflare. Our mission stays the same: to make JavaScript developers more productive than ever before. Vite, Vitest, Rolldown, Oxc, and Vite+ remain MIT-licensed. Evan and the VoidZero team will continue leading them.

Today, VoidZero joins Cloudflare. Vite remains MIT, vendor-neutral, and stewarded by the same wider team. The same goes for Vitest, Rolldown, and Oxc. Cloudflare is also committing $1M to an OSS fund to support independent development in the Vite ecosystem.

We've published a Browser Mode security advisory. CDP-capable providers like Playwright Chromium with the browser API exposed to the network allowed attackers to run code on the host. Update vitest/browser to 5.0.0-beta.4, 4.1.8, or 3.2.6. Vite+ users: Upgrade to 0.1.24 github.com/vitest-dev/v...

Building this integration has been amazing opportunity to dogfood all APIs we've added into @vitest.dev in past years. It's using features like new Reporter APIs, Vitest plugin hooks, browser commands, CDP, test tags and much more! Vitest is definitely one of the most extensible JS tools out there.

We’re launching early access for Vitest visual testing with Chromatic! ⚡️ Built with @vitest.dev core maintainer ariperkkio.dev, Chromatic adds visual testing to the browser tests you already write. 🧵 (1/4)

🦸 The legends who stayed till the very end of yesterday's #ReactSummit Pragmatic Testing workshop. I love how @vitest.dev + a resilient testing strategy makes tests look the same across frameworks.

🚨 We are publishing Vitest 4.1.6 and Vitest 5.0.0-beta.3 to resolve recent vulnerabilities: - `--api` and `--ui` exposed arbitrary files to the network - `--api` allowed arbitrary execution - `?otelCarrier` XSS Check github.com/vitest-dev/v... for more information

Couldn't keep up with all the news? We got some selected highlight from last month to recap! 🌀 → Vite Plus lazyPlugins API → @vitest.dev 5 sneak peak → Oxlint: RFC for linting Svelte/Vue/Angular templates → Module Federation in @vite.dev via plugin → @npmx.dev vp option youtu.be/zwY4UZr-qjc

🫡 Bye `fakeAsync`, thanks for your service. ✨ Angular 22 will ship an option to migrate `fakeAsync` to @vitest.dev fake timers 🗑️ No more Zone.js patching just because of `fakeAsync` 🙏 Thanks to Andrew Scott and Charles Lyding for welcoming the idea and for the feedback github.com/angular/angu...

Tales from the Void: April 2026 is out! ✨ This month at VoidZero: ◇ Our approach to supply chain security & trusted publishing ◇ A new Oxc-based Angular Compiler that is up 20x faster ◇ Vite+ `lazyPlugin` to reduce slowdowns ◇ @vitest.dev Browser Mode trace viewer ◇ @rolldown.rs module tags

@vitest.dev is going framework agnostic, and we need your feedback!

Take a first look at the new @vitest.dev Browser Mode's trace viewer 👀 Design is not final 😄 Thank you, @hiogawa.bsky.social for working on it! main.vitest.dev/guide/browse...

what are these downloads numbers 🤨

Did you know that @vitest.dev has an Agent reporter? 🤖 Instead of outputting all the details, it ensures only the failing tests and summary are sent to your agent. That means less tokens used and less information overload. Since Vitest 4.1 this is the default when detecting an agent.

There's some impressive work going on with 3rd party oxc powered coverage instrumentation that can replace Babel based istanbul-lib-instrument 👀 > 8-11x faster than babel-plugin-istanbul, 13-15x faster than swc-plugin-coverage-instrument (Rust/WASM), 25-30x faster than istanbul-lib-instrument.

Really enjoying the Storybook/Vitest integration and the accessibility addon. It's friction at its best; easily detect an issue, serve you a direct link to the documentation about the rule so you learn something as a developer + the details you need to go fix it immediately 👏

vitest no longer supporting node 18 has been a good way to get a huge number of projects to bump their minimum node version 😄

Want to start writing tests but no idea how to get started? The @vitest.dev docs now have a Learn section that covers evergreen concepts (matchers, tests, dealing with async code, mocks, ...) and also current topics like writing good tests with AI! Time to get started 🎉