Jest

Jest 30.5 lets mock functions return different values based on matched call arguments via whenCalledWith, supports retrying an entire describe block (rerunning its hooks and nested tests) with jest.retryTimes, and rewrites the non-watchman file watcher using @parcel/watcher and fdir; it also cuts module resolution and require overhead and replaces source-map-support to fix a memory leak. No breaking changes are introduced, though users are asked to test with --no-watchman to surface any regressions in the new crawler.

Matters for: Teams maintaining large Jest suites with complex mocking setups, ESM interop, or Windows-based watch-mode workflows.