events: pass the original listener added by once

When removing a `once` listener, the listener being passed to the `removeListener` callback is the wrapper. This unwraps the listener so that `removeListener` is passed the actual listener. PR-URL: #6394 Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: davidtaikocha

lib/events.js

@@ -308,7 +308,7 @@ EventEmitter.prototype.prependOnceListener =
 // emits a 'removeListener' event iff the listener was removed
 EventEmitter.prototype.removeListener=
 functionremoveListener(type,listener){
-varlist,events,position,i;
+varlist,events,position,i,originalListener;
 
 if(typeoflistener!=='function')
 thrownewTypeError('"listener" argument must be a function');
@@ -327,14 +327,15 @@ EventEmitter.prototype.removeListener =
 else{
 deleteevents[type];
 if(events.removeListener)
-this.emit('removeListener',type,listener);
+this.emit('removeListener',type,list.listener||listener);
 }
 }elseif(typeoflist!=='function'){
 position=-1;
 
 for(i=list.length;i-->0;){
 if(list[i]===listener||
 (list[i].listener&&list[i].listener===listener)){
+originalListener=list[i].listener;
 position=i;
 break;
 }
@@ -356,7 +357,7 @@ EventEmitter.prototype.removeListener =
 }
 
 if(events.removeListener)
-this.emit('removeListener',type,listener);
+this.emit('removeListener',type,originalListener||listener);
 }
 
 returnthis;

test/parallel/test-event-emitter-remove-listeners.js

@@ -102,3 +102,14 @@ e6.emit('hello');
 
 // Interal listener array [listener3]
 e6.emit('hello');
+
+conste7=newevents.EventEmitter();
+
+constlistener5=()=>{};
+
+e7.once('hello',listener5);
+e7.on('removeListener',common.mustCall((eventName,listener)=>{
+assert.strictEqual(eventName,'hello');
+assert.strictEqual(listener,listener5);
+}));
+e7.emit('hello');