Using node-mocks-http to test a service no event emitted

I have a simple service I'd like to test, by calling its controller. I thought I'd use node-mocks-http to create a mock request, and look at the results of the response. However, despite all the documentation and sample code, I could not get the response to emit any event ("end", "send" or even "error"), and can't therefore know when to test the output.

Here's a simple function (using Express 4.*):

export function getServiceHealth(req, res) {
  let message = 'service has been up for ' + process.uptime() + ' seconds!';
  res.status(200).send(message);
}

Here's my test (Jasmine):

import {EventEmitter} from 'events';
import httpMock from 'node-mocks-http';
import {getServiceHealth} from '../../lib/controllers/health/';

describe('Service health integration tests', () => {
  it('should get health', done => {
    let req = httpMock.createRequest({url: '/health'});
    let res = httpMock.createResponse({EventEmitter: EventEmitter});
    getServiceHealth(req, res);
    res.on('end', () => {
      console.log(res._getData());
      done();
    });
    res.on('send', () => {
      console.log(res._getData());
      done();
    });
    //setTimeout(() => {console.log(res._getData()); done();}, 1000);
  });
});

The only way I ever get this test to finish (without throwing a timeout error) is by uncommenting the setTimeout line - obviously not the right way to go. And when I do, the data in res is exactly what I expect it to be - meaning that other than event firing, everything works ok.

What do I have to do to get the event triggered on res?

PS: on the off chance that this is some ES6 import shenanigan, I tried this:

let res = httpMock.createResponse({EventEmitter: require('events').EventEmitter});

Same result.

PPS: Opened issue on repo