How to test ServiceStack Service using Moq

I have a rest service that I have created with ServiceStack, using nHibernate as a way of getting the data from a SqlCe database. I've been trying to write some unit tests using nUnit and Moq - I have successfully mocked the nHibernate implementation to return null, invalid objects and so on - but my tests always throw a NullReferenceException when it calls the base class to set the HttpStatus etc.

public List <ParameterDto> Get (ParameterAll parameterAll)
    {
        List <ParameterDto> parameterResponseList = new List <ParameterDto> ();
        try
        {
            List <ParameterDomainObject> parameterDomainObjectList = _ParameterDao.getAllParameters ();
            foreach (ParameterDomainObject parameterDomainObject in parameterDomainObjectList)
            {
                parameterResponseList.Add (parameterDomainObject.ToDto ());
            }
        }
        catch (WebServiceException webEx)
        {
            Debug.WriteLine ("WebServiceException.ErrorCode         " + webEx.ErrorCode);
            Debug.WriteLine ("WebServiceException.ErrorMessage      " + webEx.ErrorMessage);
            Debug.WriteLine ("WebServiceException.ResponseStatus    " + webEx.ResponseStatus);
            Debug.WriteLine ("WebServiceException.StatusCode        " + webEx.StatusCode);
            Debug.WriteLine ("WebServiceException.StatusDescription " + webEx.StatusDescription);
            Debug.WriteLine ("WebServiceException.ErrorCode         " + webEx.ErrorCode);
        }
        catch (DomainObjectNotFoundException domainObjectNotFoundException)
        {
            base.Response.StatusCode = (int) HttpStatusCode.NotFound;
            base.Response.AddHeader ("Reason",
                                     domainObjectNotFoundException.Message);
        }
        catch (Exception exception)
        {
            Debug.WriteLine ("Exception: " + exception.Message);
            base.Response.StatusCode = (int) HttpStatusCode.InternalServerError;
            base.Response.AddHeader ("Reason",
                                     exception.Message);
        }
        /* Always throws an exception here, or anywhere base.Response is called */
        base.Response.StatusCode = (int) HttpStatusCode.OK;
        base.Response.AddHeader ("Reason",
                                 Strings.ParameterRestResponse_Get_OK);
        return parameterResponseList;
    }

The service works fine when testing it with RestClient and Firefox, and when I comment out the base.Response code so I'm guessing I'm just not setting something up right in the unit tests maybe?

    [Test]
    public void Test_Method_Get_AllParameters_Unsucessful ()
    {
        Mock <IRequestContext> mockedRequestContext = new Mock<IRequestContext>();
        mockedRequestContext.SetupGet(f => f.AbsoluteUri).Returns("http:/localhost:8080/parameters/all");

        Mock<IParameterDao> mockedParameterDao = new Mock<IParameterDao>();
        mockedParameterDao.Setup (returns => returns.getAllParameters ()).Returns (new List <ParameterDomainObject> ());
        Assert.IsNotNull (mockedParameterDao);

        ParameterRestService service = new ParameterRestService(mockedParameterDao.Object)
        {
            RequestContext = mockedRequestContext.Object
        };

        List <ParameterDto> parameterDtos = service.Get (new ParameterAll ());
    }

It looks like you just need to mock the Response property of the Service class. It's protected with no setter but you should be able to mock it doing something like...

    Mock<IRequestContext> mockedRequestContext = new Mock<IRequestContext>();
    Mock<IHttpResponse> mockedResponse = new Mock<IHttpResponse>();
    mockedRequestContext.SetupGet(f => f.AbsoluteUri).Returns("http:/localhost:8080/parameters/all");
    mockedRequestContext.Setup(f => f.Get<IHttpResponse>()).Returns(mockedResponse.Object);