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davidvgalbraith wants to merge 6 commits into from
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events: make sure console functions exist #4479

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362d832
events: make sure console functions exist
Dec 30, 2015
9f8eddb
initialize console in defaultMaxListeners setter
Jan 1, 2016
04a9276
test: overwrite stderr.write instead of checking e._events
Jan 4, 2016
ff4065e
global console exists spec cleanups
Jan 11, 2016
e1a14e7
Use the default export EventEmitter from events
Jan 12, 2016
7152739
TODO validate console
Jan 12, 2016
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events: make sure console functions exist 
if there's no global console cached, these calls will initialize it,
which in some cases can cause a circular dependency, making the console
received here an empty object. The program shouldn't crash in this case.

Fixes #4467
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Dave committed Dec 30, 2015
commit 362d8320ab8a0ddfd0a646d5c9f9ec89197961c7
3 changes: 2 additions & 1 deletion lib/events.js
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Expand Up @@ -240,7 +240,8 @@ EventEmitter.prototype.addListener = function addListener(type, listener) {
'leak detected. %d %s listeners added. ' +
'Use emitter.setMaxListeners() to increase limit.',
existing.length, type);
console.trace();
if (console.trace)
console.trace();
}
}
}
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3 changes: 2 additions & 1 deletion lib/internal/util.js
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Expand Up @@ -25,7 +25,8 @@ exports.error = function(msg) {
args[0] = fmt;
for (let i = 1; i < arguments.length; ++i)
args[i] = arguments[i];
console.error.apply(console, args);
if (console.error)
console.error.apply(console, args);
} else {
console.error(fmt);
}
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21 changes: 21 additions & 0 deletions test/parallel/test-global-console-exists.js
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@@ -0,0 +1,21 @@
'use strict';

const assert = require('assert');
const events = require('events');

const old_default = events.defaultMaxListeners;
events.defaultMaxListeners = 1;

const e = new events.EventEmitter();
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@thefourtheye thefourtheye Jan 11, 2016

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Redundant EventEmitter

e.on('hello', function() {});

assert.ok(!e._events['hello'].hasOwnProperty('warned'));
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@mscdex mscdex Dec 30, 2015

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Perhaps it would be better to use a public API to check, such as:

assert.ok(!e.listeners('hello')[0].hasOwnProperty('warned'));

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@davidvgalbraith davidvgalbraith Dec 30, 2015

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The listeners() API leaves out the warned property: https://github.com/nodejs/node/blob/master/lib/events.js#L393.

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@jasnell jasnell Jan 4, 2016

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While I agree that it's the most efficient approach, using an internal API in a test is a bit troublesome. The "correct" way to do this would likely be to direct the stderr/stdout output to a stream and apply a regex to ensure that the result is as the user should expect it to be. It's a bit of a workaround but it ensures that we're testing exactly what the user would see.


e.on('hello', function() {});

assert.ok(e._events['hello'].hasOwnProperty('warned'));

events.defaultMaxListeners = old_default;

// this caches console, so place it after the test just to appease the linter
require('../common');
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@silverwind silverwind Jan 11, 2016

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A better solution would be to put a /* eslint-disable required-modules */ on top of this file, along with a comment.