stream: do cleanup when iterator is destroyed

PR-URL: nodejs#42320
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Nitzan Uziely <linkgoron@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/streams/readable.js

@@ -1122,7 +1122,7 @@ async function* createAsyncIterator(stream, options) {
   stream.on('readable', next);
 
   let error;
-  eos(stream, { writable: false }, (err) => {
+  const cleanup = eos(stream, { writable: false }, (err) => {
     error = err ? aggregateTwoErrors(error, err) : null;
     callback();
     callback = nop;
@@ -1150,6 +1150,9 @@ async function* createAsyncIterator(stream, options) {
       (error === undefined || stream._readableState.autoDestroy)
     ) {
       destroyImpl.destroyer(stream, null);
+    } else {
+      stream.off('readable', next);
+      cleanup();
     }
   }
 }

test/parallel/test-stream-readable-async-iterators.js

@@ -789,6 +789,20 @@ async function tests() {
       }
     );
   }
+
+  // Check for dangling listeners
+  (async function() {
+    const readable = createReadable();
+    const opts = { destroyOnReturn: false };
+    while (readable.readable) {
+      // eslint-disable-next-line no-unused-vars
+      for await (const chunk of readable.iterator(opts)) {
+        break;
+      }
+    }
+
+    assert.deepStrictEqual(readable.eventNames(), []);
+  })().then(common.mustCall());
 }
 
 {