How to create a mock HttpWebRequest and HttpWebResponse object

How to create mock HttpWebRequest and HttpWebResponse object I am trying to unittest the following piece of code

HttpWebrequest request;   

if (null != request)
{                         
    var response = (HttpWebResponse)request.GetResponse();
    using (var sr = new StreamReader(response.GetResponseStream()))
    {
        jsonResult = sr.ReadToEnd();
    }

    var myRecords = SerializationHelper.Deserialize<Records>(jsonResult);
}