events: make sure console functions exist

Dave · jasnell · commit f9a59c1d3bf8 · 2016-01-14T18:20:25.000-08:00
If there's no global console cached, initialize it. Fixes: #4467 PR-URL: #4479 Reviewed-By: Roman Reiss <me@silverwind.io> Reviewed-By: James M Snell <jasnell@gmail.com>
diff --git a/lib/events.js b/lib/events.js
@@ -19,7 +19,20 @@ EventEmitter.prototype._maxListeners = undefined;
 
 // By default EventEmitters will print a warning if more than 10 listeners are
 // added to it. This is a useful default which helps finding memory leaks.
-EventEmitter.defaultMaxListeners = 10;
+var defaultMaxListeners = 10;
+
+Object.defineProperty(EventEmitter, 'defaultMaxListeners', {
+  enumerable: true,
+  get: function() {
+    return defaultMaxListeners;
+  },
+  set: function(arg) {
+    // force global console to be compiled.
+    // see https://github.com/nodejs/node/issues/4467
+    console;
+    defaultMaxListeners = arg;
+  }
+});
 
 EventEmitter.init = function() {
   this.domain = null;
diff --git a/test/parallel/test-global-console-exists.js b/test/parallel/test-global-console-exists.js
@@ -0,0 +1,36 @@
+/* eslint-disable required-modules */
+// ordinarily test files must require('common') but that action causes
+// the global console to be compiled, defeating the purpose of this test
+
+'use strict';
+
+const assert = require('assert');
+const EventEmitter = require('events');
+const leak_warning = /EventEmitter memory leak detected\. 2 hello listeners/;
+
+var write_calls = 0;
+process.stderr.write = function(data) {
+  if (write_calls === 0)
+    assert.ok(data.match(leak_warning));
+  else if (write_calls === 1)
+    assert.ok(data.match(/Trace/));
+  else
+    assert.ok(false, 'stderr.write should be called only twice');
+
+  write_calls++;
+};
+
+const old_default = EventEmitter.defaultMaxListeners;
+EventEmitter.defaultMaxListeners = 1;
+
+const e = new EventEmitter();
+e.on('hello', function() {});
+e.on('hello', function() {});
+
+// TODO: figure out how to validate console. Currently,
+// there is no obvious way of validating that console
+// exists here exactly when it should.
+
+assert.equal(write_calls, 2);
+
+EventEmitter.defaultMaxListeners = old_default;
