fix(jest-worker): postMessage error handler in child threads

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Fixes
 
 - `[jest-core]` Fix typo in `scheduleAndRun` performance marker ([#14434](https://github.com/jestjs/jest/pull/14434))
+- `[jest-worker]` Additional error wrapper for `parentPort.postMessage` to fix unhandled `DataCloneError`. ([#14437](https://github.com/jestjs/jest/pull/14437))
 
 ### Chore & Maintenance
 

packages/jest-worker/src/workers/__tests__/threadChild.test.ts

@@ -365,3 +365,24 @@ it('throws if child is not forked', () => {
     messagePort.emit('message', [CHILD_MESSAGE_CALL, true, 'fooThrows', []]);
   }).toThrow('_worker_threads.parentPort.postMessage is not a function');
 });
+
+it('handle error if `postMessage` throws an error', () => {
+  messagePort.emit('message', [
+    CHILD_MESSAGE_INITIALIZE,
+    true,
+    './my-fancy-worker',
+  ]);
+
+  jest.mocked(messagePort.postMessage).mockImplementationOnce(() => {
+    throw mockError;
+  });
+
+  messagePort.emit('message', [CHILD_MESSAGE_CALL, true, 'fooWorks', []]);
+  expect(jest.mocked(messagePort.postMessage).mock.calls[1][0]).toEqual([
+    PARENT_MESSAGE_CLIENT_ERROR,
+    'TypeError',
+    'Boo',
+    mockError.stack,
+    {},
+  ]);
+});

packages/jest-worker/src/workers/threadChild.ts

@@ -112,7 +112,14 @@ function reportSuccess(result: unknown) {
     throw new Error('Child can only be used on a forked process');
   }
 
-  parentPort!.postMessage([PARENT_MESSAGE_OK, result]);
+  try {
+    parentPort!.postMessage([PARENT_MESSAGE_OK, result]);
+  } catch (err: any) {
+    // Handling it here to avoid unhandled `DataCloneError` rejection
+    // which is hard to distinguish on the parent side
+    // (such error doesn't have any message or stack trace)
+    reportClientError(err);
+  }
 }
 
 function reportClientError(error: Error) {