Jest is a comprehensive JavaScript testing solution that works out of the box for most JavaScript projects. It provides fast interactive watch mode (running related tests for changed files) and supports snapshot testing to track how large objects change over time.
Project status
- Jest (jestjs/jest) appears actively maintained, with a very recent upstream push on 2026-06-02, and multiple Jest v30.x updates in May and March 2026.
- The apparent update cadence is fairly steady in the v30 series, with several updates clustered in early May 2026 (v30.4.0 to v30.4.2 within about two days), plus additional updates in late March 2026 (v30.3.0) and late September 2025 (v30.2.0).
AI summary generated
Recent updates
v30.4.2
Jest v30.4.2 focuses on fixing ESM/CJS interop in jest-runtime, specifically named imports when a CJS module sets `module.exports` to a function that also has own-property exports. The code change expands how `buildCjsAsEsmSyntheticModule` interprets `module.exports`, and adds end-to-end and unit coverage for this interop scenario.
v30.4.1
v30.4.1 adds support for configuring custom test runners with runner options via a tuple form, and ensures runner options are propagated into the runner at construction time. It also aligns Jest's CJS-from-ESM default export behavior with Node's behavior by adjusting __esModule unwrapping.
BreakingFeaturesv30.4.0
v30.4.0 is a major Jest release focused on a rewrite of the custom runtime to better support native ESM behaviors and upcoming stabilization work. It adds Node 24.9+ support for require() of ESM (still requiring --experimental-vm-modules), expands Temporal support in fake timers, and improves React 19 snapshot formatting. The release also introduces several CLI/config enhancements (for collecting test names without running them, graceful worker exits, and jest.config.mts).
Featuresv30.3.0
Jest v30.3.0 adds new configuration helpers (defineConfig and mergeConfig) for type-safe config authoring, and introduces jest.setTimerTickMode to control how fake timers advance. The release also includes multiple bug fixes across config handling, reporters, runtime ESM behavior, test sequencing, and small maintenance work like picomatch adoption and a sinon fake-timers update.
BreakingFeaturesv30.2.0
Jest v30.2.0 primarily adds support for JSDOM v27 in the jsdom abstract test environment. Release notes also mention a babel-jest typing fix (exporting `TransformerConfig`) and a documentation-related fix for `jest.config.ts` TS loader pragma handling. The code diff includes additional internal changes related to Babel 8 compatibility and the babel-plugin-jest-hoist plugin factory behavior that are not mentioned in the release notes.
Featuresv30.1.3
Jest v30.1.3 includes a fix for mocking Node.js built-in core modules when they are referenced with the `node:` prefix. The change is implemented in Jest's module resolution logic, and new E2E coverage is added to prevent regressions.
v30.1.2
Release 30.1.2 is a patch release with a targeted fix in `@jest/snapshot-utils` related to how snapshot headers are parsed across operating systems. In addition to the code change, the monorepo version numbers are bumped from 30.1.1 to 30.1.2 across many packages.
v30.1.1
Jest v30.1.1 includes a targeted fix in `@jest/snapshot-utils` for handling Windows (CRLF) line endings when dealing with deprecated `goo.gl` snapshot guide URLs. The change primarily updates snapshot header parsing and extends test coverage for both ` ` and ` ` formats.
v30.1.0
Jest v30.1.0 adds new configuration and runtime behavior improvements, including configurable GC aggressiveness for jest-leak-detector and changes to how jest-core handles the --onlyFailures mode. It also includes several fixes across expect, snapshots, and jest-circus, plus CI/documentation updates.
BreakingFeaturesv30.0.2
Release v30.0.2 contains two documented fixes related to Jest internal safety around object copying and garbage collection protection. The code diff confirms both changes, primarily in jest-matcher-utils and jest-util. It also includes an undocumented test harness change that alters when a specific test runs.