Vitest is a unit testing framework for JavaScript. Up to now, many teams have relied on Jest, but Jest doesn't play well with Vite, a modern front-end build tool. Using Jest and Vite together forced teams to create two pipelines — one for build and development and one for unit testing — which required tedious configuration of the pipelines with duplicate settings. These problems are solved with Vitest. It is designed specifically for Vite and uses Vite as a bundler. As an additional feature, Vitest has Jest-compatible APIs which makes it possible to use Vitest as a drop-in replacement for Jest in various build setups. However, using Vite and Vitest together provides a better developer experience, and although Vitest is fast, in our experience, it isn't necessarily faster than using Jest.
