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();
    });
});

@@ -295,12 +295,153 @@
     %7D);%0A
+    it('captcha object should be an instance of Captcha class', function()%7B%0A        expect(captcha instanceof Captcha).toBeTruthy();%0A    %7D);%0A
 %7D);%0A

Add test if captcha is instance of Captcha class