Migration Guide #

Migrating from Jest #

Vitest has been designed with a Jest compatible API, in order to make the migration from Jest as simple as possible. Despite those efforts, you may still run into the following differences:

Globals as a Default

Jest has their globals API enabled by default. Vitest does not. You can either enable globals via the globals configuration setting or update your code to use imports from the vitest module instead.

If you decide to keep globals disabled, be aware that common libraries like testing-library will not run auto DOM cleanup.

Auto-Mocking Behaviour

Unlike Jest, mocked modules in <root>/__mocks__ are not loaded unless vi.mock() is called. If you need them to be mocked in every test, like in Jest, you can mock them inside setupFiles.

Jasmine API

Jest exports various jasmine globals (such as jasmine.any()). Any such instances will need to be migrated to their Vitest counterparts.

Envs

Just like Jest, Vitest sets NODE_ENV to test, if it wasn't set before. Vitest also has a counterpart for JEST_WORKER_ID called VITEST_WORKER_ID, so if you rely on it, don't forget to rename it.

Done Callback

From Vitest v0.10.0, the callback style of declaring tests is deprecated. You can rewrite them to use async/await functions, or use Promise to mimic the callback style.

- it('should work', (done) => {
+ it('should work', () => new Promise(done => {
    // ...
    done()
- })
+ }))

Vue Snapshots

This is not a Jest specific feature, but if you previously were using Jest with vue-cli preset, you will need to install jest-serializer-vue package, and use it inside setupFiles:

import vueSnapshotSerializer from 'jest-serializer-vue'

// Add Snapshot Serializer
expect.addSnapshotSerializer(vueSnapshotSerializer)

Otherwise your snapshots will have a lot of escaped " characters.