event-emitter-example.spec.ts

import { EventEmitter } from 'events';
import { expect } from 'chai';
import { stub } from 'sinon';
import { eventEmitterExample } from '../src/event-emitter-example';

describe.only('eventEmitterExample()', () => {

	beforeEach(() => {
		stub(console, 'info');
		stub(console, 'error');
	});

	it('shoud log info something that happen when somethingHappen is emitted', () => {
		const emitter = new EventEmitter();

		const result = eventEmitterExample(emitter);
		emitter.emit('somethingHappen', 'You got what you want!');

		expect(console.info).to.have.been.calledOnceWithExactly('Something happened! You got what you want!');
		expect(console.error).to.have.not.been.called;
		expect(result).to.be.undefined;
	});

	it('shoud log error something went wrong when sometingGoesWrong is emitted', () => {
		const emitter = new EventEmitter();

		const result = eventEmitterExample(emitter);
		emitter.emit('sometingGoesWrong', 'You got what you deserve!');

		expect(console.info).to.have.not.been.called;
		expect(console.error).to.have.been.calledOnceWithExactly('Something went wrong! You got what you deserve!');
		expect(result).to.be.undefined;
	});
});