React Daily: Clearing the Path to Jest 30
A cluster of test-infrastructure PRs from eps1lon is prepping React's test suite for a Jest 30 upgrade, while three separate DOM and hydration fixes tighten up event handling edge cases. No breaking changes for app developers, but the groundwork here reduces flaky tests and unblocks future tooling upgrades.
Duration: PT2M49S
Episode overview
This episode is a short developer briefing from React Daily.
It explains recent repository work in plain language.
- Show: React Daily
- Published: 2026-08-27T06:00:41Z
- Audio duration: PT2M49S
Transcript excerpt
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It's August 27th, 2026, and this is React Daily.
The dominant story today is test infrastructure. Several PRs are clearing obstacles for a Jest 30 upgrade, and one bug fix along the way turned up a real reliability issue.
Start with PR 37384 and its matching commit, 269bd40: the team removed a custom "toThrow" matcher override that existed only to normalize old V8 error message formats for Node 12 through 16. Since React now runs Node 20 and 24, that shim was dead weight — and worse, it deep-imported an internal Jest path that…
Alongside that, commit 3c397fe fixed something more interesting: mocked performance clocks were leaking across test files. Because Jest's Node environment shares one performance object by reference across a worker process, a test that overrode "performance.now" directly could leave that fake clock active for every…
Rounding out the Jest 30 push: PR 37385 unpins jsdom, letting it float to the version Jest's own jsdom environment expects, and PR 37380 fixes a Babel resolution conflict in the compiler package's test transform.
Second theme: small but concrete DOM correctness fixes. PR 37389 makes sure the "source" property on toggle events actually reaches your…
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