Vitest v4.0.9 — Release Notes & Engineering Impact

Source available — automated, not human-reviewed

Component: vitest · Channel: stable. Automated analysis, not a compatibility certification. How this works.

Analysis updated: 2026-11-01.

Compatibility not verified — check source notes

📄 .MD

✨ Features 1 🔧 Bug Fixes 4

⚡ Executive Summary (TL;DR)

Vitest v4.0.9. Source highlight:    🚀 Experimental Features

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Who Does This Impact? (Role-Based Analysis)

💻 Software Engineers & Devs

Check the source notes against the package and APIs you use before upgrading.

📊 Product & Engineering Leads

Use the documented changes to assess relevance to your product; release frequency alone is not a quality measure.

⚙️ DevOps & Security

Verify the target version, runtime requirements and rollback procedure in the official documentation.

✨ New Features & Capabilities (1)

**expect**: Add Set support to toBeOneOf  -  by @tim-we and @sheremet-va in https://github.com/vitest-dev/vitest/issues/8906 <samp>(a415d)</samp>

🔧 Bug Fixes & Patches (4)

**browser**: Add favicon icons to the browser mode ui  -  by @userquin in https://github.com/vitest-dev/vitest/issues/8972 <samp>(353ee)</samp>
**forks**: Increase worker start timeout  -  by @AriPerkkio in https://github.com/vitest-dev/vitest/issues/9027 <samp>(5e750)</samp>
**jsdom**: Cloned request is an instance of `Request`  -  by @sheremet-va in https://github.com/vitest-dev/vitest/issues/8985 <samp>(506a9)</samp>
**ui**: Collect file/suite/test duration correctly  -  by @userquin in https://github.com/vitest-dev/vitest/issues/8976 <samp>(8016d)</samp>

📄 View Raw Release Notes (Original Developer Log)

###    🚀 Experimental Features - **expect**: Add Set support to toBeOneOf  -  by @tim-we and @sheremet-va in https://github.com/vitest-dev/vitest/issues/8906 [<samp>(a415d)</samp>](https://github.com/vitest-dev/vitest/commit/a415d0375) ###    🐞 Bug Fixes - **browser**: Add favicon icons to the browser mode ui  -  by @userquin in https://github.com/vitest-dev/vitest/issues/8972 [<samp>(353ee)</samp>](https://github.com/vitest-dev/vitest/commit/353ee5bbc) - **forks**: Increase worker start timeout  -  by @AriPerkkio in https://github.com/vitest-dev/vitest/issues/9027 [<samp>(5e750)</samp>](https://github.com/vitest-dev/vitest/commit/5e750f4ba) - **jsdom**: Cloned request is an instance of `Request`  -  by @sheremet-va in https://github.com/vitest-dev/vitest/issues/8985 [<samp>(506a9)</samp>](https://github.com/vitest-dev/vitest/commit/506a9fd0f) - **ui**: Collect file/suite/test duration correctly  -  by @userquin in https://github.com/vitest-dev/vitest/issues/8976 [<samp>(8016d)</samp>](https://github.com/vitest-dev/vitest/commit/8016da886) #####     [View changes on GitHub](https://github.com/vitest-dev/vitest/compare/v4.0.8...v4.0.9)

← Older Version Vitest v4.0.8 Newer Version → Vitest v4.0.10