HTTPEXTENSION METHOD

public static class HttpRequestMessageExtensions
{
    public static HttpResponseMessage CreateInvalidJsonResponse(this HttpRequestMessage request)
    {
        return request.CreateResponse<InvalidJson>(HttpStatusCode.BadRequest, new InvalidJson());
    }
}

TEST

[TestFixture]
    public class ShowControllerTest
    {
        private ShowController _showController;
        private IShowService _showService;

        [SetUp]
        public void Setup()
        {
            _showService = MockRepository.GenerateMock<IShowService>();
            _showController = new ShowController(_showService);


            var httpRequest = new HttpRequestMessage(HttpMethod.Post, "http://localhost/");
            var config = new HttpConfiguration();
            httpRequest.Properties[HttpPropertyKeys.HttpConfigurationKey]= config;
            _showController.Request = httpRequest;
            _showController.Configuration = config;
            var route = config.Routes.MapHttpRoute("DefaultApi", "api/{controller}/{id}");
            var routeData = new HttpRouteData(route, new HttpRouteValueDictionary(new { controller = "show" }));
            _showController.Request.Properties[HttpPropertyKeys.HttpRouteDataKey]= routeData;

        }



        [Test]
        public void ProcessShows_Should_Return_InvalidJsonResponse_When_Request_Is_Invalid()
        {
            //Arrange
            var request = new GenericRequest<Show>();

            //Act
            request = null;
            _showController.ProcessShows(request);

            //Assert
        }
    }

CONTROLLER

 [RoutePrefix("")]
    public class ShowController : ApiController
    {
        private readonly IShowService _showService;

        public ShowController(IShowService showService)
        {
            _showService = showService;
        }
 [Route("")]
        [HttpPost]
        public HttpResponseMessage ProcessShows([FromBody] GenericRequest<Show> request)
        {
                            //Return if invalid json
                if (request == null)
                    return Request.CreateInvalidJsonResponse();

}

I have searched around and people are saying to add HttpPropertyKeys.HttpConfigurationKey which i have but still it isn't working .

throws The request does not have an associated configuration object or the provided configuration was null.