old_contents: describe("The constructor is supposed a proper Captcha object", function() {
      it('Constructor Captcha exists', function(){
          expect(Captcha).toBeDefined();
      });
      var captcha = new Captcha();
      it("Captcha object is not null", function(){
         expect(captcha).not.toBeNull();
      });
  });
  
new_contents: describe("The constructor is supposed a proper Captcha object", function() {
      it('Constructor Captcha exists', function(){
          expect(Captcha).toBeDefined();
      });
      var captcha = new Captcha();
      it("Captcha object is not null", function(){
         expect(captcha).not.toBeNull();
      });
      it('captcha object should be an instance of Captcha class', function(){
          expect(captcha instanceof Captcha).toBeTruthy();
      });
  });
  
subject: Add test if captcha is instance of Captcha class