node/test/parallel/test-event-emitter-once.js
cjihrig e57ff455e2 test: exercise EE function type checking paths
This commit adds tests for on(), once(), removeListener(),
and prependOnceListener(), which all throw a TypeError if
the listener argument is not a function.

PR-URL: https://github.com/nodejs/node/pull/8168
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
2016-09-09 19:50:56 -04:00

37 lines
780 B
JavaScript

'use strict';
const common = require('../common');
const assert = require('assert');
const EventEmitter = require('events');
const e = new EventEmitter();
e.once('hello', common.mustCall(function(a, b) {}));
e.emit('hello', 'a', 'b');
e.emit('hello', 'a', 'b');
e.emit('hello', 'a', 'b');
e.emit('hello', 'a', 'b');
var remove = function() {
common.fail('once->foo should not be emitted');
};
e.once('foo', remove);
e.removeListener('foo', remove);
e.emit('foo');
e.once('e', common.mustCall(function() {
e.emit('e');
}));
e.once('e', common.mustCall(function() {}));
e.emit('e');
// Verify that the listener must be a function
assert.throws(() => {
const ee = new EventEmitter();
ee.once('foo', null);
}, /^TypeError: "listener" argument must be a function$/);