fix: do not report unref-ed subprocesses as open handles

CHANGELOG.md

@@ -75,6 +75,7 @@
 - `[jest-config]` [**BREAKING**] Add `mjs` and `cjs` to default `moduleFileExtensions` config ([#12578](https://github.com/facebook/jest/pull/12578))
 - `[jest-config, jest-haste-map]` Allow searching for tests in `node_modules` by exposing `retainAllFiles` ([#11084](https://github.com/facebook/jest/pull/11084))
 - `[jest-core]` [**BREAKING**] Exit with status `1` if no tests are found with `--findRelatedTests` flag ([#12487](https://github.com/facebook/jest/pull/12487))
+- `[jest-core]` Do not report unref-ed subprocesses as open handles ([#12705](https://github.com/facebook/jest/pull/12705))
 - `[jest-each]` `%#` is not replaced with index of the test case ([#12517](https://github.com/facebook/jest/pull/12517))
 - `[jest-each]` Fixes error message with incorrect count of missing arguments ([#12464](https://github.com/facebook/jest/pull/12464))
 - `[jest-environment-jsdom]` Make `jsdom` accessible to extending environments again ([#12232](https://github.com/facebook/jest/pull/12232))

e2e/__tests__/detectOpenHandles.ts

@@ -108,6 +108,17 @@ it('does not report timeouts using unref', () => {
   expect(textAfterTest).toBe('');
 });
 
+it('does not report child_process using unref', () => {
+  // The test here is basically that it exits cleanly without reporting anything (does not need `until`)
+  const {stderr} = runJest('detect-open-handles', [
+    'child_process',
+    '--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__/child_process.js

@@ -0,0 +1,21 @@
+/**
+ * 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 {spawn} = require('child_process');
+
+test('something', () => {
+  const subprocess = spawn(
+    process.argv[0],
+    [require.resolve('../interval-code')],
+    {
+      detached: true,
+      stdio: 'ignore',
+    },
+  );
+  subprocess.unref();
+  expect(true).toBe(true);
+});

e2e/detect-open-handles/interval-code.js

@@ -0,0 +1,10 @@
+/**
+ * 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.
+ */
+
+setInterval(() => {
+  console.log('XX');
+}, 1000);

packages/jest-core/src/collectHandles.ts

@@ -93,24 +93,19 @@ export default function collectHandles(): HandleCollectionResult {
       if (fromUser) {
         let isActive: () => boolean;
 
-        if (type === 'Timeout' || type === 'Immediate') {
-          // Timer that supports hasRef (Node v11+)
-          if ('hasRef' in resource) {
-            if (hasWeakRef) {
-              // @ts-expect-error: doesn't exist in v12 typings
-              const ref = new WeakRef(resource);
-              isActive = () => {
-                return ref.deref()?.hasRef() ?? false;
-              };
-            } else {
-              isActive = resource.hasRef.bind(resource);
-            }
+        // Handle that supports hasRef
+        if ('hasRef' in resource) {
+          if (hasWeakRef) {
+            // @ts-expect-error: doesn't exist in v12 typings
+            const ref = new WeakRef(resource);
+            isActive = () => {
+              return ref.deref()?.hasRef() ?? false;
+            };
           } else {
-            // Timer that doesn't support hasRef
-            isActive = alwaysActive;
+            isActive = resource.hasRef.bind(resource);
           }
         } else {
-          // Any other async resource
+          // Handle that doesn't support hasRef
           isActive = alwaysActive;
         }