chore: add test that unreffed workers are not reported (#12798)

e2e/__tests__/detectOpenHandles.ts

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import {onNodeVersions} from '@jest/test-utils';
 import runJest, {runContinuous} from '../runJest';
 
 function getTextAfterTest(stderr: string) {
@@ -119,6 +120,19 @@ it('does not report child_process using unref', () => {
   expect(textAfterTest).toBe('');
 });
 
+onNodeVersions('>=18.1.0', () => {
+  it('does not report worker using unref', () => {
+    // The test here is basically that it exits cleanly without reporting anything (does not need `until`)
+    const {stderr} = runJest('detect-open-handles', [
+      'worker',
+      '--detectOpenHandles',
+    ]);
+    const textAfterTest = getTextAfterTest(stderr);
+
+    expect(textAfterTest).toBe('');
+  });
+});
+
 it('prints out info about open handlers from inside tests', async () => {
   const run = runContinuous('detect-open-handles', [
     'inside',

e2e/detect-open-handles/__tests__/worker.js

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const {Worker} = require('worker_threads');
+
+test('something', () => {
+  const worker = new Worker(require.resolve('../interval-code'), {
+    stderr: true,
+    stdout: true,
+  });
+  worker.unref();
+  expect(true).toBe(true);
+});