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'use strict';
const common = require('../common');
const assert = require('assert');
const EventEmitter = require('events');
{
const ee = new EventEmitter();
const events_new_listener_emited = [];
const listeners_new_listener_emited = [];
// Sanity check
assert.strictEqual(ee.addListener, ee.on);
ee.on('newListener', function(event, listener) {
// Don't track newListener listeners.
if (event === 'newListener')
return;
events_new_listener_emited.push(event);
listeners_new_listener_emited.push(listener);
});
const hello = common.mustCall(function(a, b) {
assert.strictEqual('a', a);
assert.strictEqual('b', b);
});
ee.once('newListener', function(name, listener) {
assert.strictEqual(name, 'hello');
assert.strictEqual(listener, hello);
assert.deepStrictEqual(this.listeners('hello'), []);
});
ee.on('hello', hello);
ee.once('foo', common.fail);
assert.deepStrictEqual(['hello', 'foo'], events_new_listener_emited);
assert.deepStrictEqual([hello, common.fail], listeners_new_listener_emited);
ee.emit('hello', 'a', 'b');
}
// just make sure that this doesn't throw:
{
const f = new EventEmitter();
f.setMaxListeners(0);
}
{
const listen1 = function listen1() {};
const listen2 = function listen2() {};
const ee = new EventEmitter();
ee.once('newListener', function() {
assert.deepStrictEqual(ee.listeners('hello'), []);
ee.once('newListener', function() {
assert.deepStrictEqual(ee.listeners('hello'), []);
});
ee.on('hello', listen2);
});
ee.on('hello', listen1);
// The order of listeners on an event is not always the order in which the
// listeners were added.
assert.deepStrictEqual(ee.listeners('hello'), [listen2, listen1]);
}
// Verify that the listener must be a function
assert.throws(() => {
const ee = new EventEmitter();
ee.on('foo', null);
}, /^TypeError: "listener" argument must be a function$/);
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