Vitest 2.0 Released: Forks Pool Default and Browser Mode Groundwork

What happened

Vitest 2.0 was released on July 8, 2024, according to the official GitHub release notes. It introduced several breaking changes alongside significant new features, particularly around the test runner's execution model and browser testing.

Forks pool by default

A key breaking change was switching the default worker pool from threads to forks, done for compatibility reasons. The release notes acknowledged the forks pool may be slightly slower than the previous threads pool but is more robust, and removed the --segfault-retry flag that had existed to combat thread segfaults, recommending the new default instead. Chai was also updated to version 5.

Browser Mode groundwork

Vitest 2.0 laid the groundwork for the next iteration of Browser Mode. It added commands to communicate between the server and the browser, avoided reloading the page during watch mode, implemented userEvent methods such as fill and dragAndDrop, added an expect.dom method that bundles jest-dom matchers, and added an option to take screenshots when a browser test fails.

Reporting and API additions

The release added a blob reporter, letting Vitest run in separate processes and combine reports later with a --merge-reports flag, plus an expect.poll utility, a test.for helper, and a vitest list API to print collected tests without running them. It also rendered tests in a tree in the UI and replaced the navigation tree with a test explorer.

Why it mattered

Vitest 2.0 prioritised stability by defaulting to the more compatible forks pool, and invested heavily in browser testing, a growing need as component testing moved into real browsers. The blob reporter and merge-reports workflow, meanwhile, made Vitest more practical for large, sharded CI runs.

Related on Skillo

See also: Vitest 1.0 and its stable release, Vitest 3.0's Vite 6 support.

Sources

• Vitest v2.0.0 release notes (GitHub)

Published date reflects the original event date (2024-07-08). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.