C# ASP.NET表单身份验证-返回带有JSON响应的身份验证Cookie

我正试图以编程方式登录到我自己的web应用程序来执行一些屏幕抓取操作，以便运行一些自动化测试。当前，当用户登录系统时，调用以下方法：

[HttpPost]
public ActionResult Login(LoginModel model, string returnUrl) {
   // login logic -- ASP.NET Forms Authentication
   // do i need to send more back here? or change my return?
   return this.Json(new { resultText = "Success", ReturnUrl = returnUrl });
}

是否有某种方法可以让我在这里返回所需的信息，以便使用响应的代码可以存储这些信息，然后将其与后续请求一起发送回去

HttpWebRequest request = WebRequest.Create(loginUrl) as HttpWebRequest;
// login request comes back successful

HttpWebResponse httpResponse = request .GetResponse() as HttpWebResponse;
// read authentication info here from response

HttpWebRequest request2 = WebRequest.Create(pageUrl) as HttpWebRequest;
// include authentication info here

。。。还是我完全走错了路