Vitest

v5.0.0 is in release-candidate stage with rc.3, adding nested project support, Temporal mocking without fake timers, and a pluggable benchmark provider API.

Project configuration got more flexible — and stricter.

• Nested projects are supported, and inline projects now extend the root config by default.
• Config resolution is separated from server creation, and config files are no longer looked up from ancestor directories.
• injectCjsGlobals and fsModuleCache are now top-level options.

Mocking and assertions tightened up.

• Temporal can be mocked without fake timers; mocks are cleared by default before each test.
• Tests now fail when an asynchronous assertion isn't awaited.
• Redirect mocks are restricted to the fs allowlist.

Browser and UI workflows improved.

• browser.expect.toMatchScreenshot gained a screenshotDirectory config; the webdriverio package was removed.
• The UI highlights editor source locations, supports keyboard navigation of trace steps, and persists trace state.
• The GitHub Actions reporter supports a custom summary title.

Coverage and benchmark internals were reworked.

• Coverage switched to @vitest/istanbuljs packages, and parseSpecifications is no longer experimental.
• A pluggable benchmark provider API was added.

VS Code extension kept pace.

• Deno 2.8 is supported, diagnostics are tagged as Vitest, and Windows drive letters are normalized in failure stacks.

v4.1.x and v3.2.x backports fixed browser session readiness, iframe URL encoding, and importOriginal with optimizer queries.