Testing the Deserialization of RestSharp without proper REST-Api

Question

EDIT: The solution to the question can be found in the first comment by John Sheehan!

i would like to use Restsharp as Rest-Client for my Project. Since the REST server is not running yet, I would like to test the client without the Server. My main focus is on the deserialization of the returning XML-Response. Is it possible to deserialize XML using RestSharp without a proper RestSharp.RestResponse?

I tried it like this:

public void testDeserialization()
{
    XmlDeserializer d = new XmlDeserializer();
    RestSharp.RestResponse response = new RestSharp.RestResponse();
    string XML = @"<Response><Item1>Some text</Item1><Item2>Another text</Item2><Item3>Even more text</Item3></Response>";
    response.Content = XML;

    d.RootElement = "Response";
    Response r = d.Deserialize<Response>(response);
}

public class Response
{
    public string Item1 { get; set; }
    public string Item2 { get; set; }
    public string Item3 { get; set; }
}

The deserializations creates an Object of the Response-Class, where every field is null. Is there a way to test if (and how) any given xml would be deserialized by RestSharp?

Edit: For better readability - this is the XML i'm using:

<Response>
    <Item1>Some text</Item1>
    <Item2>Another text</Item2>
    <Item3>Even more text</Item3>
</Response>