TL;DR
Gutenberg’s JavaScript unit and integration tests now use Vitest, bringing better support for modern JavaScript modules and real-browser component testing.
Tests explicitly import Vitest APIs. Filenames select Node, jsdom, or Browser Mode according to what each test needs.
@wordpress/scripts 36.0.0 makes Vitest the default for test-unit-js. Projects install and configure their own test runner.
Existing projects can keep their Jest tests through test-unit-jest, after a one-time setup update. This command receives maintenance support and has no scheduled removal.
@wordpress/jest-preset-default and @wordpress/jest-console are deprecated. Published versions remain available for existing projects. No replacement WordPress Vitest preset or console packages are planned.
Following the initial announcement in #core-editor, Gutenberg has completed its migration from Jest to Vitest for JavaScript unit and integration tests.
