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'use strict';
const common = require('../common');
const { once, EventEmitter } = require('events');
const { strictEqual, deepStrictEqual } = require('assert');
class EventTargetMock {
constructor() {
this.events = {};
}
addEventListener = common.mustCall(function(name, listener, options) {
if (!(name in this.events)) {
this.events[name] = { listeners: [], options };
}
this.events[name].listeners.push(listener);
});
removeEventListener = common.mustCall(function(name, callback) {
if (!(name in this.events)) {
return;
}
const event = this.events[name];
const stack = event.listeners;
for (let i = 0, l = stack.length; i < l; i++) {
if (stack[i] === callback) {
stack.splice(i, 1);
if (stack.length === 0) {
Reflect.deleteProperty(this.events, name);
}
return;
}
}
});
dispatchEvent = function(name, ...arg) {
if (!(name in this.events)) {
return true;
}
const event = this.events[name];
const stack = event.listeners.slice();
for (let i = 0, l = stack.length; i < l; i++) {
stack[i].apply(this, arg);
if (event.options.once) {
this.removeEventListener(name, stack[i]);
}
}
return !name.defaultPrevented;
};
}
async function onceAnEvent() {
const ee = new EventEmitter();
process.nextTick(() => {
ee.emit('myevent', 42);
});
const [value] = await once(ee, 'myevent');
strictEqual(value, 42);
strictEqual(ee.listenerCount('error'), 0);
strictEqual(ee.listenerCount('myevent'), 0);
}
async function onceAnEventWithTwoArgs() {
const ee = new EventEmitter();
process.nextTick(() => {
ee.emit('myevent', 42, 24);
});
const value = await once(ee, 'myevent');
deepStrictEqual(value, [42, 24]);
}
async function catchesErrors() {
const ee = new EventEmitter();
const expected = new Error('kaboom');
let err;
process.nextTick(() => {
ee.emit('error', expected);
});
try {
await once(ee, 'myevent');
} catch (_e) {
err = _e;
}
strictEqual(err, expected);
strictEqual(ee.listenerCount('error'), 0);
strictEqual(ee.listenerCount('myevent'), 0);
}
async function stopListeningAfterCatchingError() {
const ee = new EventEmitter();
const expected = new Error('kaboom');
let err;
process.nextTick(() => {
ee.emit('error', expected);
ee.emit('myevent', 42, 24);
});
process.on('multipleResolves', common.mustNotCall());
try {
await once(ee, 'myevent');
} catch (_e) {
err = _e;
}
process.removeAllListeners('multipleResolves');
strictEqual(err, expected);
strictEqual(ee.listenerCount('error'), 0);
strictEqual(ee.listenerCount('myevent'), 0);
}
async function onceError() {
const ee = new EventEmitter();
const expected = new Error('kaboom');
process.nextTick(() => {
ee.emit('error', expected);
});
const [err] = await once(ee, 'error');
strictEqual(err, expected);
strictEqual(ee.listenerCount('error'), 0);
strictEqual(ee.listenerCount('myevent'), 0);
}
async function onceWithEventTarget() {
const et = new EventTargetMock();
process.nextTick(() => {
et.dispatchEvent('myevent', 42);
});
const [ value ] = await once(et, 'myevent');
strictEqual(value, 42);
strictEqual(Reflect.has(et.events, 'myevent'), false);
}
async function onceWithEventTargetTwoArgs() {
const et = new EventTargetMock();
process.nextTick(() => {
et.dispatchEvent('myevent', 42, 24);
});
const value = await once(et, 'myevent');
deepStrictEqual(value, [42, 24]);
}
async function onceWithEventTargetError() {
const et = new EventTargetMock();
const expected = new Error('kaboom');
process.nextTick(() => {
et.dispatchEvent('error', expected);
});
const [err] = await once(et, 'error');
strictEqual(err, expected);
strictEqual(Reflect.has(et.events, 'error'), false);
}
Promise.all([
onceAnEvent(),
onceAnEventWithTwoArgs(),
catchesErrors(),
stopListeningAfterCatchingError(),
onceError(),
onceWithEventTarget(),
onceWithEventTargetTwoArgs(),
onceWithEventTargetError(),
]).then(common.mustCall());
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