title: TypeError: Cannot read property 'address' of undefined supertest
body: <p>I need some help to resolve my problem with testing on nodejs codes. I'm using mocha and supertest. I'm confused with the implementation in supertest. I don't know to resolved it. I'm trying to automate downloading a file.</p>
  
  <pre><code>describe('GET /entry/:entryId/file/:id/download', function(){
      it('should pass download function', function(done){
          this.timeout(15000);
          request(app.webServer)
              .get('/entry/543CGsdadtrE/file/wDRDasdDASAS/download')
              .set('Authorization', 'Bearer eyJ0eXAiOiJKV1QiLCJhbGco')
              .expect(200)
              .end(function(err, res) {
                  if (err) return done(err);
                  console.log(err, res);
                  done();
              });
      });
  });
  </code></pre>