Next generation testing framework powered by Vite.

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Documentation | Getting Started | Examples | Why Vitest?

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• 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

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!

See Contributing Guide.

MIT License © 2021-Present Anthony Fu, Matias Capeletto