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From Jest to Vitest - Migration and Benchmark

Matti Bar-Zeev on January 21, 2022

In this post join me as I migrate my project’s test runner framework from Jest to Vitest, and check if it is really as they claim - “A blazing fast...
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Matt Morgan

My friends, family and colleagues told me I shouldn't run off after another test framework, but now I know we're right and they're wrong. Thanks for this article!

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Jonathan Higger • Edited

I've been using vitest because of remix stacks. Almost everything feels the same as jest but I notice a few things pragmatically.

Pros

  • nicer coloring
  • faster tests
  • less finnicky config maybe

Cons

  • it seems to crash a bit more often
  • .only and .skip don't seem to work as well for me
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The Builder

jest setup has been stressing me out all day, I'm happy that at I came across vitest today and then this article helped me solve the document is not defined issue that i ran into when using vitest. Thanks for writing

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Matti Bar-Zeev

Glad I could help 🍻

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Imamuzzaki Abu Salam

Love this ❤️

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Matti Bar-Zeev

Thanks!

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Roee Fl

You showed how to define setupFiles in vite.config, but you did not reference the contents of setupTests.js.

Could you include what should be in there for the Chai issue to resolve?

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Nibble

Thank you for this post!
Can I use vitest for company new project now?

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Matti Bar-Zeev

I believe you can, but make sure it answers all your company's needs

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Emil

Vitest is not that fast as it pretends to be. Jest is faster in most cases, because usually you expect isolation in tests, but Vitest has problems with performance. Here is a Github issue github.com/vitest-dev/vitest/issue....

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Rob Levin

I’m definitely keeping my eyes on vitest and this post makes me wanna give it another shot (forget exactly why but had trouble getting it working a few weeks back) but the whole philosophy of vitest is really compelling. Thanks for the nice case study!

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Matti Bar-Zeev

With pleasure :)

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Lars Ejaas

Oh, that looked surprisingly simple!
I am still a bit unsure how enzyme would fit into the Vitest environment and how easy it is to setup with next.js - but the Vitest project sounds SO promising!

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Emil

It is suggested to drop enzyme tests, because it is not supported any more. Keeping aside that it brings questionable value.

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Lars Ejaas

Thanks Emil. I have also come to that conclusion myself 🙂

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vaishnavi1029

Remix Vite plugin can't detect preamble. Something is wrong.
❯ app/routes/stored.tsx:2:8
1| export default function Comp(){
2| return <h1>jcs</h1>

Error: Remix Vite plugin can't detect preamble. Something is wrong.
here is my vite.config
///
///
import { vitePlugin as remix } from "@remix-run/dev";
import { installGlobals } from "@remix-run/node";
import { defineConfig } from "vite";
import tsconfigPaths from "vite-tsconfig-paths";
installGlobals();

export default defineConfig({
test:{
environment:"jsdom",
globals: true,
setupFiles: ["./set-up-test.env.ts"],
},
plugins: [
remix({
ignoredRouteFiles: ["*/.css"],
}),
tsconfigPaths(),

],

});
can you help me solve this

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Rob OLeary • Edited

I hope vitest gets more traction and becomes a solid alternative to jest for vue and svelte also soon. thanks for the write-up

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Naeemo

Thank you for this post, just like a "TL,DR" for me to migrate to vitest.

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Matti Bar-Zeev

Cheers :) Just remember that this is not production ready yet, according to their readme.

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Tom Byrer

Hard to tell how much improvement there is, since we don't know how many & how complicated the tests are.

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Tim Ritzer

I mean he literally said it was 4 test files, and 37 tests. A small sample size, sure, but large enough to show relative progress.

I'd love to see some numbers for larger codebases, but that's tough since the software is still considered not production ready.

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Matti Bar-Zeev • Edited

True. I won't use my little PoC here to determine whether or not you should use Vitest, but I do say it does look promising.

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Alon Segal

as always, love to read your articles!
their comment on not being ready for production and the tight coupling to vite will cause me to wait some more :)

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Matti Bar-Zeev

Cheers :)
Yeah, I'd wait for it some a little bit more

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LuisPa

Great post!