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jmuransky · 2026-04-22T08:57:22Z

Helps solve the issue from #15275

The idea behind it -> ESM modules need to be compiled in async mode while CJS needs to be compiled in sync mode. To get to this state, we need to basically resolve all module dependencies before we even start to compile.

The only way I could think of how to get to this state is to - open the file, walk thru it via AST, pull all imports and create import tree (graph) from it. Leaf imports do not depend on anything, so we can directly import them. Then we can walk up the tree (graph) which in the end handles all the imports while keeping CJS imports synchronous (they see compiled module in cache).

Summary

Motivation for this was, that my project - a mixture of ESM+CJS modules that imported each other - was crashing. This solves the issue at least in my project.

Test plan

I added test that spawns new jest runner that actually handles imports (and exits successfully).

Disclosure

I used AI when writing this - but it should not be visible. I verified every line of code. I asked very specific tasks out of it instead of "solve this". The algorithm/idea is mine - AI just wrote it and helped me debug issues (and write tests). But I know precisely what every line does and why it's there (and that it can't be removed).

Note

Feel free to edit anything/everything from this pull request. I expect some parts could be optimized for better performance.

It might be possible, that there's better AST parser for this (or there's entirely different solution for this) and I am fine with using that.
One thing that you might also consider - given my solution, each file should get resolved at least 2x (once for preloading dependencies and once for actual transformation). This probably could be cached (file reading actually is cached).

On the flip side - this solution should not slow jest a lot if the project does not import cjs-esm-cjs too much.

Cjs esm interoperability experiment

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linux-foundation-easycla · 2026-04-22T08:57:28Z

The committers listed above are authorized under a signed CLA.

✅ login: jmuransky / name: Gandor (15dfda6, 1b7031f, 202dbf4, 2c53b57, 318530e, 323d68b, 4247e17, 4a34436, 57bbf5a, 5ab6590, 5e2bcb5, 6925bd5, 858dd4a, 8ceeca4, 905fd2d, 959f396, a0e7a5b, aa79ec2, b69e2de, c2bb35c, c6b0eec, e0948b0, ee0961d, f53796e)
✅ login: jmuransky / name: Juraj Muransky (bc125ef)
✅ login: SimenB / name: Simen Bekkhus (0e5f802, 5c68287, ca0b354, cee3085, d043d8d, f8f3ed3)

pkg-pr-new · 2026-04-22T09:59:24Z

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commit: cee3085

…t scope

… native node resolution, which prevents our active code to register the wait for it)

…and over (possibly creating infinite loop), add unpacking for cjs modules when default-imported from esm package

…port dependency graph order evaluation)

…y cases

…ot skipped by default

jmuransky · 2026-04-23T15:44:50Z

I don't know how to fix these last 2 checks without changing global jest project's unit test configuration (am I allowed to do that?).
My whole functionality is about ESM/CJS interaction so there's no reasonable way to write unit tests to raise coverage, that tests something I wrote and while not having --experimental-vm-modules turned on.

…ompat tests

…from cjs project - for both jasmine and circus runner

… should not have been resolved)

SimenB · 2026-04-24T14:14:06Z

Thanks! I've been thinking of picking up require(esm) in the last couple of days due to node upstream picking up the ESM vm APIs again (nodejs/node#62720 for reference ). Will make sure to look through this at the same time 🙂 maaaaybe over the weekend, but I don't wanna make any promises 😅

SimenB · 2026-04-29T07:36:48Z

If you wanna review it, I'd very much welcome it! 🙂 but don't feel obliged. I'd rather you first change this PR so its bug fixes can land 👍

… (with slow AST walking the source code)

jmuransky · 2026-04-29T22:35:50Z

It's quite late in here, so I'll need to look at this better tomorrow.

I tried the thing out, but from what I can tell right now - the linking step is always async. That would mean cjs (still needing to be synchronous) importing esm will always fail (no way to wait) if there's no way to inspect it's content ahead of time.
There are a few tests that are failing me on this thing. I'll try to figure out something tomorrow

SimenB · 2026-04-30T05:21:08Z

Linking step is async ATM yes - that sync code path will land in #16063. After that the plan is to add require(esm) as a follow-up.

But the fixes I was thinking could land from this PR aren't on the require(esm) path - they're on the existing module.link(asyncLinker) flow. Sync linking and require(esm) come later and pick up your loadCjsAsEsm fixes for free (the sync flow calls the same _buildCjsAsEsmSyntheticModule helper).

So bug fixes can land here independently of #16063 (and its yet-to-be-wrriten follow-up) - don't worry about sync linking. The failing test looks to be from e2e/native-esm-cjs-require/cjs-with-esm-req.cjs? that won't work until later and can be removed for now.

SimenB · 2026-04-30T05:44:39Z

I pushed to do a quick cleanup pass (removing the failing test as it won't work yet, removed the no longer needed deps, and added a CI run). Let's see what CI says 😀

jmuransky · 2026-04-30T05:45:32Z

Perfect. Thanks

SimenB

Thanks for taking a deep dive into the weeds of our ESM implementation 😀 I'll try to land require(esm) in the next few days and make a release 🙂

jmuransky · 2026-04-30T06:10:39Z

I am really looking forward to it.
I still wonder how you'll fix cjs project requiring esm too. If you'd remember me after doing PR. Can you ping me so I can see it please?

SimenB · 2026-04-30T06:11:40Z

Yeah, for sure 🙂

Copilot

Pull request overview

This PR updates jest-runtime’s VM-module loading flow to improve ESM↔CJS interoperability (notably around importing CJS from ESM, SyntaxError fallback to native ESM parsing, and concurrency/deadlock behavior), and adds fixtures/tests plus CI coverage to validate the new behavior under --experimental-vm-modules.

Changes:

Update jest-runtime module linking/evaluation logic to better handle concurrency and avoid deadlocks during linking/importing (including wasm import wiring).
Improve CJS-as-ESM interop: cache the wrapper module, merge static+runtime named exports, hide __esModule, and unwrap Babel-style default exports; add SyntaxError fallback to load “ESM-in-.js-without-type-module” as native ESM.
Add unit/e2e fixtures and a dedicated CI job/script to run jest-runtime tests with --experimental-vm-modules; add changelog entries.

Reviewed changes

Copilot reviewed 28 out of 28 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/jest-runtime/tsconfig.json	Adds `ESNext.Error` lib for `Error.isError` typing.
packages/jest-runtime/src/index.ts	Implements updated link/evaluate flow, CJS-as-ESM caching/interop tweaks, SyntaxError fallback, wasm deadlock avoidance.
packages/jest-runtime/src/tests/runtime_esm_cjs_interop.test.ts	Adds runtime-level tests for CJS-as-ESM behavior (gated on VM modules support).
packages/jest-runtime/src/tests/test_esm_interop_root/*	Adds fixture modules to exercise the new interop paths.
package.json	Adds scripts to run `jest-runtime` tests with `--experimental-vm-modules`.
jest.config.mjs	Ignores the new runtime fixture directory at repo root test config level.
e2e/native-esm-cjs-require/*	Adds an E2E fixture covering default unwrapping, named exports, and singleton caching.
e2e/tests/nativeEsmCjsRequire.test.ts	Adds an E2E test runner for the new fixture.
e2e/tests/snapshots/nativeEsmCjsRequire.test.ts.snap	Snapshot for the new E2E test’s summary output.
CHANGELOG.md	Adds entries describing the interop fixes.
.github/workflows/nodejs.yml	Adds a CI job to run `jest-runtime` tests with `--experimental-vm-modules`.

Copilot · 2026-04-30T06:21:29Z

  private loadCjsAsEsm(from: string, modulePath: string, context: VMContext) {
+    const registry = this._isolatedModuleRegistry ?? this._esmoduleRegistry;
+    const cached = registry.get(modulePath);
+    if (cached) {
+      return cached as SyntheticModule;
+    }


loadCjsAsEsm caches the newly created SyntheticModule in registry before evaluateSyntheticModule() completes, but the cached path returns the module synchronously. If a second importer hits the cache while the first call is still linking/evaluating, Node may attempt to link the same SyntheticModule twice (or consumers may observe it before evaluation completes). Consider caching the promise for link/evaluate (the registry supports Promise<ESModule>), and always returning/awaiting that shared promise (or only caching after the module is fully linked/evaluated).

Copilot · 2026-04-30T06:21:30Z

+    const allCandidates = new Set([
+      ...parsedExports,
+      ...Object.keys(cjs as Record<string, unknown>),
+    ]);


Object.keys(cjs as Record<string, unknown>) will throw if a CJS module sets module.exports = null (or undefined). Since CJS exports can legally be null/primitive, this path should avoid calling Object.keys / hasOwnProperty on non-objects (e.g. use Object.keys(Object(cjs)) or guard with a typeof/null check and fall back to the static export set).

Copilot · 2026-04-30T06:21:30Z

+    await this._esmModuleEvaluatingMap.get(module);
+


linkAndEvaluateModule only stores an entry in _esmModuleEvaluatingMap when it calls module.evaluate() itself. If linkAndEvaluateModule is invoked while the module is already in 'evaluating' state due to Node's evaluation cascade, there may be no cached promise and the final await this._esmModuleEvaluatingMap.get(module) becomes a no-op, returning while the module is still evaluating. Consider explicitly handling module.status === 'evaluating' (and no stored promise) by waiting until the status changes, or by ensuring an evaluation promise is recorded for all evaluation entry points.

Suggested change

await this._esmModuleEvaluatingMap.get(module);

let evalPromise = this._esmModuleEvaluatingMap.get(module);

if (evalPromise == null && module.status === 'evaluating') {

evalPromise = new Promise<void>((resolve, reject) => {

const waitForEvaluation = () => {

const status = module.status as VMModule['status'];

if (status === 'evaluated') {

resolve();

return;

}

if (status === 'errored') {

reject(module.error);

return;

}

if (status === 'evaluating') {

queueMicrotask(waitForEvaluation);

return;

}

reject(

new Error(

`Module ${module.identifier} changed to unexpected status "${status}" while evaluating.`,

),

);

};

waitForEvaluation();

});

this._esmModuleEvaluatingMap.set(module, evalPromise);

}

await evalPromise;

jmuransky · 2026-04-30T09:41:15Z

Cool :)

I'll try to check the support more over these next 3 days as current version does not run with my esm/cjs riddled project unfortunately. Might be I'll be able to help with your implementation a little

SimenB · 2026-05-01T09:18:58Z

See #16074 🙂

SimenB · 2026-05-07T19:13:53Z

https://github.com/jestjs/jest/releases/tag/v30.4.0

| datasource | package | from | to | | ---------- | ------- | ------ | ------ | | npm | jest | 30.3.0 | 30.4.0 | ## [v30.4.0](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3040) ##### Features - `[babel-jest]` Support collecting coverage from `.mts`, `.cts` (and other) files ([#15994](jestjs/jest#15994)) - `[jest-circus, jest-cli, jest-config, jest-core, jest-jasmine2, jest-types]` Add `--collect-tests` flag to discover and list tests without executing them ([#16006](jestjs/jest#16006)) - `[jest-config, jest-runner, jest-worker]` Add `workerGracefulExitTimeout` config option to control how long workers are given to exit before being force-killed ([#15984](jestjs/jest#15984)) - `[jest-config]` Add support for `jest.config.mts` as a valid configuration file ([#16005](jestjs/jest#16005)) - `[jest-config, jest-core, jest-reporters, jest-runner]` `verbose` and `silent` can now be set per-project; the project-level value overrides the global value for that project's tests ([#16133](jestjs/jest#16133)) - `[@jest/fake-timers]` Accept `Temporal.Duration` in `jest.advanceTimersByTime()` and `jest.advanceTimersByTimeAsync()` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Accept `Temporal.Instant` and `Temporal.ZonedDateTime` in `jest.setSystemTime()` and `useFakeTimers({now})` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Support faking `Temporal.Now.*` ([#16131](jestjs/jest#16131)) - `[jest-mock]` Add `clearMocksOnScope(scope)` on `ModuleMocker` for clearing every mock function exposed on a scope object ([#16088](jestjs/jest#16088)) - `[jest-resolve]` Add `canResolveSync()` on `Resolver` so callers can detect when a user-configured resolver only exports an `async` hook ([#16064](jestjs/jest#16064)) - `[jest-runtime]` Use synchronous `evaluate()` for ES modules without top-level `await` on Node versions that support it (v24.9+), and prefer the synchronous transform path when a sync transformer is configured ([#16062](jestjs/jest#16062)) - `[jest-runtime]` Support `require()` of ES modules on Node v24.9+ ([#16074](jestjs/jest#16074)) - `[jest-runtime]` Validate TC39 import attributes (`with { type: 'json' }`) on ESM imports ([#16127](jestjs/jest#16127)) - `[@jest/transform]` Add `canTransformSync(filename)` on `ScriptTransformer` so callers can pick the sync vs async transform path ([#16062](jestjs/jest#16062)) - `[jest-util]` Add `isError` helper ([#16076](jestjs/jest#16076)) - `[pretty-format]` Support React 19 ([#16123](jestjs/jest#16123)) ##### Fixes - `[expect-utils]` Fix `toStrictEqual` failing on `structuredClone` results due to cross-realm constructor mismatch ([#15959](jestjs/jest#15959)) - `[@jest/expect-utils]` Prevent `toMatchObject`/subset matching from throwing when encountering exotic iterables ([#15952](jestjs/jest#15952)) - `[fake-timers]` Convert `Date` to milliseconds before passing to `@sinonjs/fake-timers` ([#16029](jestjs/jest#16029)) - `[jest]` Export `GlobalConfig` and `ProjectConfig` TypeScript types ([#16132](jestjs/jest#16132)) - `[jest-circus]` Prevent crash when `asyncError` is undefined for non-Error throws ([#16003](jestjs/jest#16003)) - `[jest-circus, jest-jasmine2]` Include `Error.cause` in JSON `failureMessages` output ([#15967](jestjs/jest#15967)) - `[jest-config]` Fix preset path resolution on Windows when the preset uses subpath `exports` ([#15961](jestjs/jest#15961)) - `[jest-config]` Allow `collectCoverage` and `coverageProvider` in project config without a validation warning ([#16132](jestjs/jest#16132)) - `[jest-config]` Project config validator now emits "is not supported in an individual project configuration" instead of "probably a typing mistake" for known global-only options ([#16132](jestjs/jest#16132)) - `[jest-environment-node]` Fix `--localstorage-file` warning on Node 25+ ([#16086](jestjs/jest#16086)) - `[jest-reporters]` Apply global coverage threshold to unmatched pattern files in addition to glob/path thresholds ([#16137](jestjs/jest#16137)) - `[jest-reporters, jest-runner, jest-runtime, jest-transform]` Fix coverage report not showing correct code coverage when using `projects` config option ([#16140](jestjs/jest#16140)) - `[jest-runtime]` Resolve `expect` and `@jest/expect` from the internal module registry so test-file imports share the same `JestAssertionError` as the global `expect` ([#16130](jestjs/jest#16130)) - `[jest-runtime]` Improve CJS-from-ESM interop: `__esModule`/Babel default unwrap, broader named-export coverage, and shared CJS singleton across importers ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Load `.js` files with ESM syntax but no `"type":"module"` marker as native ESM ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Extend the `.js`-with-ESM-syntax fallback to `require()` on Node v24.9+ - falls back to `require(esm)` when the CJS parser rejects ESM syntax ([#16078](jestjs/jest#16078)) - `[jest-runtime]` Fix deadlocks and double-evaluation in concurrent ESM and wasm imports ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Fix error when `require()` is called after the Jest environment has been torn down ([#15951](jestjs/jest#15951)) - `[jest-runtime]` Fix missing error when `import()` is called after the Jest environment has been torn down ([#16080](jestjs/jest#16080)) - `[jest-runtime]` Fix virtual `unstable_mockModule` registrations not respected in ESM ([#16081](jestjs/jest#16081)) - `[jest-runtime]` Apply `moduleNameMapper` when resolving modules with `require.resolve()` and the `paths` option ([#16135](jestjs/jest#16135)) ##### Chore & Maintenance - `[@jest/fake-timers]` Upgrade `@sinonjs/fake-timers` ([#16139](jestjs/jest#16139)) - `[jest-runtime]` Use synchronous `linkRequests` / `instantiate` for ESM linking on Node v24.9+ ([#16063](jestjs/jest#16063))

| datasource | package | from | to | | ---------- | ------- | ------ | ------ | | npm | jest | 30.3.0 | 30.4.2 | ## [v30.4.2](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3042) ##### Fixes - `[jest-runtime]` Fix named imports from CJS modules whose `module.exports` is a function with own-property exports ([#16150](jestjs/jest#16150)) ## [v30.4.1](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3041) ##### Features - `[jest-config, jest-core, jest-runner, jest-schemas, jest-types]` Allow custom runner configuration options via tuple format `['runner-path', {options}]` ([#16141](jestjs/jest#16141)) ##### Fixes - `[jest-runtime]` Align CJS-from-ESM default export with Node: `module.exports` is always the ESM default, `__esModule` unwrapping is no longer applied ([#16143](jestjs/jest#16143)) ## [v30.4.0](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3040) ##### Features - `[babel-jest]` Support collecting coverage from `.mts`, `.cts` (and other) files ([#15994](jestjs/jest#15994)) - `[jest-circus, jest-cli, jest-config, jest-core, jest-jasmine2, jest-types]` Add `--collect-tests` flag to discover and list tests without executing them ([#16006](jestjs/jest#16006)) - `[jest-config, jest-runner, jest-worker]` Add `workerGracefulExitTimeout` config option to control how long workers are given to exit before being force-killed ([#15984](jestjs/jest#15984)) - `[jest-config]` Add support for `jest.config.mts` as a valid configuration file ([#16005](jestjs/jest#16005)) - `[jest-config, jest-core, jest-reporters, jest-runner]` `verbose` and `silent` can now be set per-project; the project-level value overrides the global value for that project's tests ([#16133](jestjs/jest#16133)) - `[@jest/fake-timers]` Accept `Temporal.Duration` in `jest.advanceTimersByTime()` and `jest.advanceTimersByTimeAsync()` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Accept `Temporal.Instant` and `Temporal.ZonedDateTime` in `jest.setSystemTime()` and `useFakeTimers({now})` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Support faking `Temporal.Now.*` ([#16131](jestjs/jest#16131)) - `[jest-mock]` Add `clearMocksOnScope(scope)` on `ModuleMocker` for clearing every mock function exposed on a scope object ([#16088](jestjs/jest#16088)) - `[jest-resolve]` Add `canResolveSync()` on `Resolver` so callers can detect when a user-configured resolver only exports an `async` hook ([#16064](jestjs/jest#16064)) - `[jest-runtime]` Use synchronous `evaluate()` for ES modules without top-level `await` on Node versions that support it (v24.9+), and prefer the synchronous transform path when a sync transformer is configured ([#16062](jestjs/jest#16062)) - `[jest-runtime]` Support `require()` of ES modules on Node v24.9+ ([#16074](jestjs/jest#16074)) - `[jest-runtime]` Validate TC39 import attributes (`with { type: 'json' }`) on ESM imports ([#16127](jestjs/jest#16127)) - `[@jest/transform]` Add `canTransformSync(filename)` on `ScriptTransformer` so callers can pick the sync vs async transform path ([#16062](jestjs/jest#16062)) - `[jest-util]` Add `isError` helper ([#16076](jestjs/jest#16076)) - `[pretty-format]` Support React 19 ([#16123](jestjs/jest#16123)) ##### Fixes - `[expect-utils]` Fix `toStrictEqual` failing on `structuredClone` results due to cross-realm constructor mismatch ([#15959](jestjs/jest#15959)) - `[@jest/expect-utils]` Prevent `toMatchObject`/subset matching from throwing when encountering exotic iterables ([#15952](jestjs/jest#15952)) - `[fake-timers]` Convert `Date` to milliseconds before passing to `@sinonjs/fake-timers` ([#16029](jestjs/jest#16029)) - `[jest]` Export `GlobalConfig` and `ProjectConfig` TypeScript types ([#16132](jestjs/jest#16132)) - `[jest-circus]` Prevent crash when `asyncError` is undefined for non-Error throws ([#16003](jestjs/jest#16003)) - `[jest-circus, jest-jasmine2]` Include `Error.cause` in JSON `failureMessages` output ([#15967](jestjs/jest#15967)) - `[jest-config]` Fix preset path resolution on Windows when the preset uses subpath `exports` ([#15961](jestjs/jest#15961)) - `[jest-config]` Allow `collectCoverage` and `coverageProvider` in project config without a validation warning ([#16132](jestjs/jest#16132)) - `[jest-config]` Project config validator now emits "is not supported in an individual project configuration" instead of "probably a typing mistake" for known global-only options ([#16132](jestjs/jest#16132)) - `[jest-environment-node]` Fix `--localstorage-file` warning on Node 25+ ([#16086](jestjs/jest#16086)) - `[jest-reporters]` Apply global coverage threshold to unmatched pattern files in addition to glob/path thresholds ([#16137](jestjs/jest#16137)) - `[jest-reporters, jest-runner, jest-runtime, jest-transform]` Fix coverage report not showing correct code coverage when using `projects` config option ([#16140](jestjs/jest#16140)) - `[jest-runtime]` Resolve `expect` and `@jest/expect` from the internal module registry so test-file imports share the same `JestAssertionError` as the global `expect` ([#16130](jestjs/jest#16130)) - `[jest-runtime]` Improve CJS-from-ESM interop: `__esModule`/Babel default unwrap, broader named-export coverage, and shared CJS singleton across importers ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Load `.js` files with ESM syntax but no `"type":"module"` marker as native ESM ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Extend the `.js`-with-ESM-syntax fallback to `require()` on Node v24.9+ - falls back to `require(esm)` when the CJS parser rejects ESM syntax ([#16078](jestjs/jest#16078)) - `[jest-runtime]` Fix deadlocks and double-evaluation in concurrent ESM and wasm imports ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Fix error when `require()` is called after the Jest environment has been torn down ([#15951](jestjs/jest#15951)) - `[jest-runtime]` Fix missing error when `import()` is called after the Jest environment has been torn down ([#16080](jestjs/jest#16080)) - `[jest-runtime]` Fix virtual `unstable_mockModule` registrations not respected in ESM ([#16081](jestjs/jest#16081)) - `[jest-runtime]` Apply `moduleNameMapper` when resolving modules with `require.resolve()` and the `paths` option ([#16135](jestjs/jest#16135)) ##### Chore & Maintenance - `[@jest/fake-timers]` Upgrade `@sinonjs/fake-timers` ([#16139](jestjs/jest#16139)) - `[jest-runtime]` Use synchronous `linkRequests` / `instantiate` for ESM linking on Node v24.9+ ([#16063](jestjs/jest#16063))

jmuransky added 6 commits April 22, 2026 01:15

preliminary working version (needs polish)

4a34436

cleanup

c6b0eec

more cleanup

a0e7a5b

add changelog entry

2c53b57

add tests

f53796e

Merge pull request #1 from jmuransky/cjs-esm-interoperability-experiment

bc125ef

Cjs esm interoperability experiment

jmuransky added 2 commits April 22, 2026 11:06

add new yarn.lock file

1b7031f

Merge branch 'main' of https://github.com/jmuransky/jest

c2bb35c

jmuransky added 2 commits April 22, 2026 12:15

explicitly push new snapshot for (new) unit test

318530e

fix cjs importing cjs should work as before, move a comment to correc…

858dd4a

…t scope

jmuransky marked this pull request as draft April 22, 2026 12:30

jmuransky added 9 commits April 22, 2026 15:39

make sure our modules are fully linked (even if they get triggered by…

4247e17

… native node resolution, which prevents our active code to register the wait for it)

add caching for cjs modules so that they don't get re-evaluated over …

959f396

…and over (possibly creating infinite loop), add unpacking for cjs modules when default-imported from esm package

fix wasm ending up in a deadlock after our linking change (reverse im…

905fd2d

…port dependency graph order evaluation)

add more unit tests covering more interesting cjs/esm interoperabilit…

15dfda6

…y cases

yarn dedupe

202dbf4

eslint fixes

ee0961d

add unit tests to raise test coverage (unblock PR)

aa79ec2

set up unit tests in a way that jest esm interoperability tests are n…

6925bd5

…ot skipped by default

fix verify-pnp error (whatever that is?)

5e2bcb5

jmuransky marked this pull request as ready for review April 23, 2026 15:41

change global configuration of unit tests to be able to run esm/cjs c…

57bbf5a

…ompat tests

jmuransky marked this pull request as draft April 24, 2026 13:11

jmuransky added 2 commits April 24, 2026 15:26

update changelog, add possibility to require transitive esm packages …

e0948b0

…from cjs project - for both jasmine and circus runner

fix issue with awaiting cjs tests even when they return promise (that…

b69e2de

… should not have been resolved)

jmuransky added 3 commits April 29, 2026 21:00

keep only bugfixes and drop esm package preloading & storing in cache…

8ceeca4

… (with slow AST walking the source code)

merge with upstream

5ab6590

remove tests testing preload functionality (obsoleted feature)

323d68b

SimenB added 2 commits April 30, 2026 07:36

remove require(esm) test and unneeded deps

ca0b354

add CI run for the VM API unit tests

5c68287

SimenB added 3 commits April 30, 2026 07:51

test should not be sharded

0e5f802

re-throw original error and avoid toctou

f8f3ed3

more in changelog

d043d8d

SimenB approved these changes Apr 30, 2026

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SimenB merged commit 1141bd4 into jestjs:main Apr 30, 2026
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This was referenced May 8, 2026

[Bug]: Jest 30.4.0 breaks CJS→ESM interop for packages with __esModule: true but no .default (e.g. tslib) #16142

Closed

fix(jest-runtime): align CJS-from-ESM default with Node, drop __esModule unwrapping #16143

Merged

nikhil-mittal-165 mentioned this pull request May 22, 2026

CHANGE @W-22270236@ - Update Node dependencies across all packages for monthly release forcedotcom/code-analyzer-core#465

Merged

-    await this._esmModuleEvaluatingMap.get(module);
+    let evalPromise = this._esmModuleEvaluatingMap.get(module);
+    if (evalPromise == null && module.status === 'evaluating') {
+      evalPromise = new Promise<void>((resolve, reject) => {
+        const waitForEvaluation = () => {
+          const status = module.status as VMModule['status'];
+          if (status === 'evaluated') {
+            resolve();
+            return;
+          }
+          if (status === 'errored') {
+            reject(module.error);
+            return;
+          }
+          if (status === 'evaluating') {
+            queueMicrotask(waitForEvaluation);
+            return;
+          }
+          reject(
+            new Error(
+              `Module ${module.identifier} changed to unexpected status "${status}" while evaluating.`,
+            ),
+          );
+        };
+        waitForEvaluation();
+      });
+      this._esmModuleEvaluatingMap.set(module, evalPromise);
+    }
+    await evalPromise;

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