events: update MaxListenersExceededWarning message log

PR-URL: https://github.com/nodejs/node/pull/51921
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/events.js

@@ -593,7 +593,7 @@ function _addListener(target, type, listener, prepend) {
       // No error code for this since it is a Warning
       const w = genericNodeError(
         `Possible EventEmitter memory leak detected. ${existing.length} ${String(type)} listeners ` +
-        `added to ${inspect(target, { depth: -1 })}. Use emitter.setMaxListeners() to increase limit`,
+        `added to ${inspect(target, { depth: -1 })}. MaxListeners is ${m}. Use emitter.setMaxListeners() to increase limit`,
         { name: 'MaxListenersExceededWarning', emitter: target, type: type, count: existing.length });
       process.emitWarning(w);
     }

lib/internal/event_target.js

@@ -561,7 +561,7 @@ class EventTarget {
       // eslint-disable-next-line no-restricted-syntax
       const w = new Error('Possible EventTarget memory leak detected. ' +
                           `${size} ${type} listeners ` +
-                          `added to ${inspect(this, { depth: -1 })}. Use ` +
+                          `added to ${inspect(this, { depth: -1 })}. MaxListeners is ${this[kMaxEventTargetListeners]}. Use ` +
                           'events.setMaxListeners() to increase limit');
       w.name = 'MaxListenersExceededWarning';
       w.target = this;

test/parallel/test-event-emitter-max-listeners-warning-for-null.js

@@ -16,7 +16,7 @@ process.on('warning', common.mustCall((warning) => {
   assert.strictEqual(warning.count, 2);
   assert.strictEqual(warning.type, null);
   assert.ok(warning.message.includes(
-    '2 null listeners added to [EventEmitter].'));
+    '2 null listeners added to [EventEmitter]. MaxListeners is 1.'));
 }));
 
 e.on(null, () => {});

test/parallel/test-event-emitter-max-listeners-warning-for-symbol.js

@@ -18,7 +18,7 @@ process.on('warning', common.mustCall((warning) => {
   assert.strictEqual(warning.count, 2);
   assert.strictEqual(warning.type, symbol);
   assert.ok(warning.message.includes(
-    '2 Symbol(symbol) listeners added to [EventEmitter].'));
+    '2 Symbol(symbol) listeners added to [EventEmitter]. MaxListeners is 1.'));
 }));
 
 e.on(symbol, () => {});

test/parallel/test-event-emitter-max-listeners-warning.js

@@ -23,7 +23,7 @@ process.on('warning', common.mustCall((warning) => {
   assert.strictEqual(warning.count, 2);
   assert.strictEqual(warning.type, 'event-type');
   assert.ok(warning.message.includes(
-    '2 event-type listeners added to [FakeInput].'));
+    '2 event-type listeners added to [FakeInput]. MaxListeners is 1.'));
 }));
 
 e.on('event-type', () => {});

test/parallel/test-eventtarget-memoryleakwarning.js

@@ -12,18 +12,21 @@ const { setTimeout } = require('timers/promises');
 common.expectWarning({
   MaxListenersExceededWarning: [
     ['Possible EventTarget memory leak detected. 3 foo listeners added to ' +
-     'EventTarget. Use events.setMaxListeners() ' +
+     'EventTarget. MaxListeners is 2. Use events.setMaxListeners() ' +
      'to increase limit'],
     ['Possible EventTarget memory leak detected. 3 foo listeners added to ' +
      '[MessagePort [EventTarget]]. ' +
+     'MaxListeners is 2. ' +
      'Use events.setMaxListeners() to increase ' +
      'limit'],
     ['Possible EventTarget memory leak detected. 3 foo listeners added to ' +
      '[MessagePort [EventTarget]]. ' +
+     'MaxListeners is 2. ' +
      'Use events.setMaxListeners() to increase ' +
      'limit'],
     ['Possible EventTarget memory leak detected. 3 foo listeners added to ' +
      '[AbortSignal]. ' +
+     'MaxListeners is 2. ' +
      'Use events.setMaxListeners() to increase ' +
      'limit'],
   ],