From d15b8ea3bdcb72b8e2dd3aee0cc717daa512d2f6 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Sat, 11 Jan 2020 13:39:34 +0100
Subject: [PATCH] stream: fix async iterator destroyed error propagation

There was an edge case where if _destroy calls the error callback
later than one tick the iterator would complete early and not
propgate the error.

PR-URL: https://github.com/nodejs/node/pull/31314
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/internal/streams/async_iterator.js        | 24 ++++++++++---------
 .../test-stream-readable-async-iterators.js   | 17 +++++++++++++
 2 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/lib/internal/streams/async_iterator.js b/lib/internal/streams/async_iterator.js
index ced9c77c4f5..8755e22de0d 100644
--- a/lib/internal/streams/async_iterator.js
+++ b/lib/internal/streams/async_iterator.js
@@ -78,18 +78,20 @@ const ReadableStreamAsyncIteratorPrototype = ObjectSetPrototypeOf({
     }
 
     if (this[kStream].destroyed) {
-      // We need to defer via nextTick because if .destroy(err) is
-      // called, the error will be emitted via nextTick, and
-      // we cannot guarantee that there is no error lingering around
-      // waiting to be emitted.
       return new Promise((resolve, reject) => {
-        process.nextTick(() => {
-          if (this[kError]) {
-            reject(this[kError]);
-          } else {
-            resolve(createIterResult(undefined, true));
-          }
-        });
+        if (this[kError]) {
+          reject(this[kError]);
+        } else if (this[kEnded]) {
+          resolve(createIterResult(undefined, true));
+        } else {
+          finished(this[kStream], (err) => {
+            if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
+              reject(err);
+            } else {
+              resolve(createIterResult(undefined, true));
+            }
+          });
+        }
       });
     }
 
diff --git a/test/parallel/test-stream-readable-async-iterators.js b/test/parallel/test-stream-readable-async-iterators.js
index 4a63e9fd302..ded77e01da3 100644
--- a/test/parallel/test-stream-readable-async-iterators.js
+++ b/test/parallel/test-stream-readable-async-iterators.js
@@ -484,6 +484,23 @@ async function tests() {
       assert.strictEqual(e, err);
     })()]);
   }
+
+  {
+    const _err = new Error('asd');
+    const r = new Readable({
+      read() {
+      },
+      destroy(err, callback) {
+        setTimeout(() => callback(_err), 1);
+      }
+    });
+
+    r.destroy();
+    const it = r[Symbol.asyncIterator]();
+    it.next().catch(common.mustCall((err) => {
+      assert.strictEqual(err, _err);
+    }));
+  }
 }
 
 {