Improve detectOpenHandles

e2e/__tests__/__snapshots__/detectOpenHandles.ts.snap

@@ -13,7 +13,7 @@ This usually means that there are asynchronous operations that weren't stopped i
 exports[`prints out info about open handlers 1`] = `
 "Jest has detected the following 1 open handle potentially keeping Jest from exiting:
 
-  ●  TCPSERVERWRAP
+  ●  DNSCHANNEL,TCPSERVERWRAP
 
       12 | const app = new Server();
       13 |

packages/jest-core/src/__tests__/collectHandles.test.js

@@ -45,9 +45,12 @@ describe('collectHandles', () => {
   it('should not collect the DNSCHANNEL open handle', async () => {
     const handleCollector = collectHandles();
 
-    const resolver = new dns.Resolver();
+    let resolver = new dns.Resolver();
     resolver.getServers();
 
+    // We must drop references to it
+    resolver = null;
+
     const openHandles = await handleCollector();
 
     expect(openHandles).not.toContainEqual(

packages/jest-core/src/collectHandles.ts

@@ -83,16 +83,7 @@ export default function collectHandles(): HandleCollectionResult {
       // Skip resources that should not generally prevent the process from
       // exiting, not last a meaningfully long time, or otherwise shouldn't be
       // tracked.
-      if (
-        type === 'PROMISE' ||
-        type === 'TIMERWRAP' ||
-        type === 'ELDHISTOGRAM' ||
-        type === 'PerformanceObserver' ||
-        type === 'RANDOMBYTESREQUEST' ||
-        type === 'DNSCHANNEL' ||
-        type === 'ZLIB' ||
-        type === 'SIGNREQUEST'
-      ) {
+      if (type === 'PROMISE') {
         return;
       }
       const error = new ErrorWithStack(type, initHook, 100);
@@ -141,14 +132,18 @@ export default function collectHandles(): HandleCollectionResult {
     // For example, Node.js TCP Servers are not destroyed until *after* their
     // `close` callback runs. If someone finishes a test from the `close`
     // callback, we will not yet have seen the resource be destroyed here.
-    await asyncSleep(100);
+    await asyncSleep(0);
 
     if (activeHandles.size > 0) {
-      // For some special objects such as `TLSWRAP`.
-      // Ref: https://github.com/facebook/jest/issues/11665
-      runGC();
+      await asyncSleep(30);
 
-      await asyncSleep(0);
+      if (activeHandles.size > 0) {
+        // For some special objects such as `TLSWRAP`.
+        // Ref: https://github.com/facebook/jest/issues/11665
+        runGC();
+
+        await asyncSleep(0);
+      }
     }
 
     hook.disable();
@@ -167,33 +162,44 @@ export function formatHandleErrors(
   errors: Array<Error>,
   config: Config.ProjectConfig,
 ): Array<string> {
-  const stacks = new Set();
-
-  return (
-    errors
-      .map(err =>
-        formatExecError(err, config, {noStackTrace: false}, undefined, true),
-      )
-      // E.g. timeouts might give multiple traces to the same line of code
-      // This hairy filtering tries to remove entries with duplicate stack traces
-      .filter(handle => {
-        const ansiFree: string = stripAnsi(handle);
-
-        const match = ansiFree.match(/\s+at(.*)/);
-
-        if (!match || match.length < 2) {
-          return true;
-        }
+  const stacks = new Map<string, {stack: string; names: Set<string>}>();
+
+  errors.forEach(err => {
+    const formatted = formatExecError(
+      err,
+      config,
+      {noStackTrace: false},
+      undefined,
+      true,
+    );
 
-        const stack = ansiFree.substr(ansiFree.indexOf(match[1])).trim();
+    // E.g. timeouts might give multiple traces to the same line of code
+    // This hairy filtering tries to remove entries with duplicate stack traces
 
-        if (stacks.has(stack)) {
-          return false;
-        }
+    const ansiFree: string = stripAnsi(formatted);
+    const match = ansiFree.match(/\s+at(.*)/);
+    if (!match || match.length < 2) {
+      return;
+    }
 
-        stacks.add(stack);
+    const stackText = ansiFree.substr(ansiFree.indexOf(match[1])).trim();
+
+    const name = ansiFree.match(/(?<=● {2}).*$/m);
+    if (!name?.length) {
+      return;
+    }
+
+    const stack = stacks.get(stackText) || {
+      names: new Set(),
+      stack: formatted.replace(name[0], '%%OBJECT_NAME%%'),
+    };
+
+    stack.names.add(name[0]);
+
+    stacks.set(stackText, stack);
+  });
 
-        return true;
-      })
+  return Array.from(stacks.values()).map(({stack, names}) =>
+    stack.replace('%%OBJECT_NAME%%', Array.from(names).join(',')),
   );
 }