What's the best way to unit test an event being emitted in Nodejs?

Question

I\'m writing a bunch of mocha tests and I\'d like to test that particular events are emitted. Currently, I\'m doing this:

  it(\'should emit an some_event\', fun         


        

Answer 1

I do it by wrapping the event in a Promise:

// this function is declared outside all my tests, as a helper
const waitForEvent = (asynFunc) => {
    return new Promise((resolve, reject) => {
        asyncFunc.on('completed', (result) => {
            resolve(result);
        }
        asyncFunc.on('error', (err) => {
            reject(err);
        }
    });
});

it('should do something', async function() {
    this.timeout(10000);  // in case of long running process
    try {
        const val = someAsyncFunc();
        await waitForEvent(someAsyncFunc);
        assert.ok(val)
    } catch (e) {
        throw e;
    }
}