title: Object is not a Function - SuperTest
body: <p>I'm not sure why it's throwing this error and what exactly it's saying is not a function.</p>
  
  <pre><code>    'use strict';
  
    var koa = require("koa");
      var app = koa();
      var chai = require('chai');
      var expect = chai.expect;
  
      var request = require('supertest');
  
      describe('Feature: Car REST Endpoint', function () {
  
          context('Scenario: GET a Car', function () {
  
              var url = 'http://localhost/search/cars';
  
              describe('Given: the resource is accessed at the resource url' + url, function () {
  
                  describe('Then: we receive a successful response', function(){
  
                      it('status code should be 200', function (done){
                          request(app)
                              .get(url)
                              .expect(200,done);
                      });
                  });
  </code></pre>
  
  <p>it says it's the line .expect(200,done) but I might be wrong.</p>
  
  <p>I also tried this with no luck:</p>
  
  <pre><code> request(app)
                      .get(url)
                      .expect(200)
                      .end(function(err, res){
                          if (err) return done(err);
                          done()
                      });
  </code></pre>
  
  <p>I also tried <code>var request = require('supertest').agent(koa);</code></p>
  
  <p><img src="https://i.stack.imgur.com/ZzJEm.png" alt="enter image description here"></p>