Vitest

Next generation testing framework powered by Vite.

Documentation | Getting Started | Examples | Why Vitest?

Features

Vite's config, transformers, resolvers, and plugins. Use the same setup from your app!
Jest Snapshot
Chai built-in for assertions, with Jest expect compatible APIs
Smart & instant watch mode, like HMR for tests!
Native code coverage via v8 or istanbul.
Tinyspy built-in for mocking, stubbing, and spies.
JSDOM and happy-dom for DOM and browser API mocking
Browser Mode for running component tests in the browser
Components testing (Vue, React, Svelte, Lit, Marko)
Workers multi-threading via Tinypool (a lightweight fork of Piscina)
Benchmarking support with Tinybench
Workspace support
expect-type for type-level testing
ESM first, top level await
Out-of-box TypeScript / JSX support
Filtering, timeouts, concurrent for suite and tests
Sharding support
Run your tests in the browser natively (experimental)

Vitest requires Vite >=v5.0.0 and Node >=v18.0.0

import { assert, describe, expect, it } from 'vitest'

describe('suite name', () => {
  it('foo', () => {
    expect(1 + 1).toEqual(2)
    expect(true).to.be.true
  })

  it('bar', () => {
    assert.equal(Math.sqrt(4), 2)
  })

  it('snapshot', () => {
    expect({ foo: 'bar' }).toMatchSnapshot()
  })
})

$ npx vitest

Credits

Thanks to:

The Jest team and community for creating a delightful testing API
@lukeed for the work on uvu where we are inspired a lot from.
@pi0 for the idea and implementation of using Vite to transform and bundle the server code.
The Vite team for brainstorming the initial idea.
@patak-dev for the awesome package name!