From 1158f44599ece58276196cf298e1f4ba1023a195 Mon Sep 17 00:00:00 2001
From: jseagull <jseagull@aliyun.com>
Date: Mon, 10 Oct 2016 18:47:07 +0800
Subject: [PATCH] events,test: fix TypeError in EventEmitter warning

Allows Symbol to be converted to String so it can be included in the
error.

Conflicts:
	lib/events.js

Fixes: #9003
Backport-PR-URL: https://github.com/nodejs/node/pull/12459
PR-URL: https://github.com/nodejs/node/pull/9021
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
---
 lib/events.js                                 |  5 ++--
 ...test-event-emitter-check-listener-leaks.js |  8 +++++++
 ...-emitter-max-listeners-warning-for-null.js | 22 +++++++++++++++++
 ...mitter-max-listeners-warning-for-symbol.js | 24 +++++++++++++++++++
 ...est-event-emitter-max-listeners-warning.js |  1 +
 5 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 test/parallel/test-event-emitter-max-listeners-warning-for-null.js
 create mode 100644 test/parallel/test-event-emitter-max-listeners-warning-for-symbol.js

diff --git a/lib/events.js b/lib/events.js
index ac18327ef147f6..5cb837cc6c3877 100644
--- a/lib/events.js
+++ b/lib/events.js
@@ -257,8 +257,9 @@ function _addListener(target, type, listener, prepend) {
       if (m && m > 0 && existing.length > m) {
         existing.warned = true;
         const w = new Error('Possible EventEmitter memory leak detected. ' +
-                            `${existing.length} ${type} listeners added. ` +
-                            'Use emitter.setMaxListeners() to increase limit');
+                            `${existing.length} ${String(type)} listeners ` +
+                            'added. Use emitter.setMaxListeners() to ' +
+                            'increase limit');
         w.name = 'Warning';
         w.emitter = target;
         w.type = type;
diff --git a/test/parallel/test-event-emitter-check-listener-leaks.js b/test/parallel/test-event-emitter-check-listener-leaks.js
index 244bfa97bfa86a..5b9787f1b83bba 100644
--- a/test/parallel/test-event-emitter-check-listener-leaks.js
+++ b/test/parallel/test-event-emitter-check-listener-leaks.js
@@ -13,6 +13,14 @@ assert.ok(!e._events['default'].hasOwnProperty('warned'));
 e.on('default', function() {});
 assert.ok(e._events['default'].warned);
 
+// symbol
+const symbol = Symbol('symbol');
+e.setMaxListeners(1);
+e.on(symbol, function() {});
+assert.ok(!e._events[symbol].hasOwnProperty('warned'));
+e.on(symbol, function() {});
+assert.ok(e._events[symbol].hasOwnProperty('warned'));
+
 // specific
 e.setMaxListeners(5);
 for (let i = 0; i < 5; i++) {
diff --git a/test/parallel/test-event-emitter-max-listeners-warning-for-null.js b/test/parallel/test-event-emitter-max-listeners-warning-for-null.js
new file mode 100644
index 00000000000000..62b06f67d92f28
--- /dev/null
+++ b/test/parallel/test-event-emitter-max-listeners-warning-for-null.js
@@ -0,0 +1,22 @@
+// Flags: --no-warnings
+// The flag suppresses stderr output but the warning event will still emit
+'use strict';
+
+const common = require('../common');
+const events = require('events');
+const assert = require('assert');
+
+const e = new events.EventEmitter();
+e.setMaxListeners(1);
+
+process.on('warning', common.mustCall((warning) => {
+  assert.ok(warning instanceof Error);
+  assert.strictEqual(warning.name, 'Warning');
+  assert.strictEqual(warning.emitter, e);
+  assert.strictEqual(warning.count, 2);
+  assert.strictEqual(warning.type, null);
+  assert.ok(warning.message.includes('2 null listeners added.'));
+}));
+
+e.on(null, function() {});
+e.on(null, function() {});
diff --git a/test/parallel/test-event-emitter-max-listeners-warning-for-symbol.js b/test/parallel/test-event-emitter-max-listeners-warning-for-symbol.js
new file mode 100644
index 00000000000000..97bf189270395b
--- /dev/null
+++ b/test/parallel/test-event-emitter-max-listeners-warning-for-symbol.js
@@ -0,0 +1,24 @@
+// Flags: --no-warnings
+// The flag suppresses stderr output but the warning event will still emit
+'use strict';
+
+const common = require('../common');
+const events = require('events');
+const assert = require('assert');
+
+const symbol = Symbol('symbol');
+
+const e = new events.EventEmitter();
+e.setMaxListeners(1);
+
+process.on('warning', common.mustCall((warning) => {
+  assert.ok(warning instanceof Error);
+  assert.strictEqual(warning.name, 'Warning');
+  assert.strictEqual(warning.emitter, e);
+  assert.strictEqual(warning.count, 2);
+  assert.strictEqual(warning.type, symbol);
+  assert.ok(warning.message.includes('2 Symbol(symbol) listeners added.'));
+}));
+
+e.on(symbol, function() {});
+e.on(symbol, function() {});
diff --git a/test/parallel/test-event-emitter-max-listeners-warning.js b/test/parallel/test-event-emitter-max-listeners-warning.js
index bcbb583265805c..df363e43d9cbb7 100644
--- a/test/parallel/test-event-emitter-max-listeners-warning.js
+++ b/test/parallel/test-event-emitter-max-listeners-warning.js
@@ -15,6 +15,7 @@ process.on('warning', common.mustCall((warning) => {
   assert.strictEqual(warning.emitter, e);
   assert.strictEqual(warning.count, 2);
   assert.strictEqual(warning.type, 'event-type');
+  assert.ok(warning.message.includes('2 event-type listeners added.'));
 }));
 
 e.on('event-type', function() {});