request('http://localhost:3000')
  .get('/api/employees')
  .expect(200)
  .expect('Content-Type', 'application/json')
  .expect(function(res) {
      if (!res.body.hasOwnProperty('name')) throw new Error("Expected 'name' key!");
      if (!res.body.hasOwnProperty('city')) throw new Error("Expected 'city' key!");
  })
  .end(function(err, res) {
      if (err) throw err;
  });