The documentation for once states:
Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected when the EventEmitter emits 'error'. The Promise will resolve with an array of all the arguments emitted to the given event.
It's not clear from the documentation what happens when once is used to listen for error event. In my case this is the desired behaviors but I was surprised when my tests were not failing because an error event was emitted.
This:
const { EventEmitter, once } = require('events');
const ee = new EventEmitter();
once(ee, 'error').then(([err]) => {
console.log('resolves', err);
}).catch((err) => {
console.log('rejects', err);
})
ee.emit('error', new Error('Hi'))Prints:
resolves Error: Hi
at Object.<anonymous> ...
Can you clarify this behaviour in the documentation please?
The documentation for once states:
It's not clear from the documentation what happens when once is used to listen for
errorevent. In my case this is the desired behaviors but I was surprised when my tests were not failing because an error event was emitted.This:
Prints:
Can you clarify this behaviour in the documentation please?