events: fix adding abort listener in events.once()

lib/events.js

@@ -969,6 +969,8 @@ async function once(emitter, name, options = {}) {
  };
  eventTargetAgnosticAddListener(emitter, name, resolver, { once: true });
  if (name !== 'error' && typeof emitter.once === 'function') {
+ // EventTarget does not have `error` event semantics like Node
+ // EventEmitters, we listen to `error` events only on EventEmitters.
  emitter.once('error', errorListener);
  }
  function abortListener() {
@@ -1008,9 +1010,7 @@ function eventTargetAgnosticAddListener(emitter, name, listener, flags) {
  emitter.on(name, listener);
  }
  } else if (typeof emitter.addEventListener === 'function') {
- // EventTarget does not have `error` event semantics like Node
- // EventEmitters, we do not listen to `error` events here.
- emitter.addEventListener(name, (arg) => { listener(arg); }, flags);
+ emitter.addEventListener(name, listener, flags);
  } else {
  throw new ERR_INVALID_ARG_TYPE('emitter', 'EventEmitter', emitter);
  }

test/parallel/test-events-once.js

@@ -1,5 +1,5 @@
 'use strict';
-// Flags: --no-warnings
+// Flags: --expose-internals --no-warnings
 
 const common = require('../common');
 const { once, EventEmitter } = require('events');
@@ -9,6 +9,7 @@ const {
  fail,
  rejects,
 } = require('assert');
+const { kEvents } = require('internal/event_target');
 
 async function onceAnEvent() {
  const ee = new EventEmitter();
@@ -65,6 +66,32 @@ async function catchesErrors() {
  strictEqual(ee.listenerCount('myevent'), 0);
 }
 
+async function catchesErrorsWithAbortSignal() {
+ const ee = new EventEmitter();
+ const ac = new AbortController();
+ const signal = ac.signal;
+
+ const expected = new Error('boom');
+ let err;
+ process.nextTick(() => {
+ ee.emit('error', expected);
+ });
+
+ try {
+ const promise = once(ee, 'myevent', { signal });
+ strictEqual(ee.listenerCount('error'), 1);
+ strictEqual(signal[kEvents].size, 1);
+
+ await promise;
+ } catch (e) {
+ err = e;
+ }
+ strictEqual(err, expected);
+ strictEqual(ee.listenerCount('error'), 0);
+ strictEqual(ee.listenerCount('myevent'), 0);
+ strictEqual(signal[kEvents].size, 0);
+}
+
 async function stopListeningAfterCatchingError() {
  const ee = new EventEmitter();
 
@@ -165,7 +192,10 @@ async function abortSignalAfterEvent() {
  ee.emit('foo');
  ac.abort();
  });
- await once(ee, 'foo', { signal: ac.signal });
+ const promise = once(ee, 'foo', { signal: ac.signal });
+ strictEqual(ac.signal[kEvents].size, 1);
+ await promise;
+ strictEqual(ac.signal[kEvents].size, 0);
 }
 
 async function abortSignalRemoveListener() {
@@ -221,6 +251,7 @@ Promise.all([
  onceAnEventWithNullOptions(),
  onceAnEventWithTwoArgs(),
  catchesErrors(),
+ catchesErrorsWithAbortSignal(),
  stopListeningAfterCatchingError(),
  onceError(),
  onceWithEventTarget(),