fix: jest-worker can return null for getStdout()

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Fixes
 
 - `[expect]` Compare DOM nodes even if there are multiple Node classes ([#8064](https://github.com/facebook/jest/pull/8064))
+- `[jest-worker]` `worker.getStdout()` can return `null` ([#8083](https://github.com/facebook/jest/pull/8083))
 
 ### Chore & Maintenance
 

packages/jest-worker/src/types.ts

@@ -49,8 +49,8 @@ export interface WorkerInterface {
     onProcessEnd: OnEnd,
   ): void;
   getWorkerId(): number;
-  getStderr(): NodeJS.ReadableStream;
-  getStdout(): NodeJS.ReadableStream;
+  getStderr(): NodeJS.ReadableStream | null;
+  getStdout(): NodeJS.ReadableStream | null;
   onExit(exitCode: number): void;
   onMessage(message: ParentMessage): void;
 }

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

@@ -166,25 +166,15 @@ export default class ChildProcessWorker implements WorkerInterface {
     this._child.send(request);
   }
 
-  getWorkerId(): number {
+  getWorkerId() {
     return this._options.workerId;
   }
 
-  getStdout(): NodeJS.ReadableStream {
-    if (this._child.stdout === null) {
-      throw new Error(
-        'stdout is null - this should never happen. Please open up an issue at https://github.com/facebook/jest',
-      );
-    }
+  getStdout() {
     return this._child.stdout;
   }
 
-  getStderr(): NodeJS.ReadableStream {
-    if (this._child.stderr === null) {
-      throw new Error(
-        'stderr is null - this should never happen. Please open up an issue at https://github.com/facebook/jest',
-      );
-    }
+  getStderr() {
     return this._child.stderr;
   }
 }

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

@@ -150,15 +150,15 @@ export default class ExperimentalWorker implements WorkerInterface {
     this._worker.postMessage(request);
   }
 
-  getWorkerId(): number {
+  getWorkerId() {
     return this._options.workerId;
   }
 
-  getStdout(): NodeJS.ReadableStream {
+  getStdout() {
     return this._worker.stdout;
   }
 
-  getStderr(): NodeJS.ReadableStream {
+  getStderr() {
     return this._worker.stderr;
   }
 }