package.json

{
  "name": "testing_bug",
  "version": "1.0.0",
  "description": "Bug?",
  "main": "''",
  "scripts": {
    "test": "mocha test.js"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "chai": "^3.5.0",
    "express": "^4.14.0",
    "mocha": "^3.0.2",
    "supertest": "^2.0.0"
  }
}

test.js

var expect = require('chai').expect;
var request = require('supertest');
var express = require('express');

describe('Testing requests and errors', function() {
  var app;

  before(function setup() {
    app = express();
    app.get('/foo', function(req, res) {
      app.emit('hi');
      res.send(200);
    });
    app.foo = function(req, res) {
      setTimeout(function() {
        app.emit('hi');
      }, 100);
    };
  });

  it('should fail fast, but times out instead', function(done) {
    app.on('hi', function() {
      console.log('got event'); // this happens
      expect(true).to.equal(false); // this should cause the test to fail
    });

    request(app)
      .get('/foo')
      .end(function(err) {});
  });

  it('should fail', function(done) {
    app.on('hi', function() {
      expect(true).to.equal(false);
    });

    app.foo();
  });

  it('should fail', function(done) {
    app.on('hi', function() {
      expect(true).to.equal(false);
    });

    app.emit('hi');
  });
});