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// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
'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');
const 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$/);
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