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'use strict';
const common = require('../common');
const { once, EventEmitter } = require('events');
const { strictEqual, deepStrictEqual } = require('assert');
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);
}
Promise.all([
onceAnEvent(),
onceAnEventWithTwoArgs(),
catchesErrors(),
stopListeningAfterCatchingError(),
onceError()
]).then(common.mustCall());
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