public void TestListInvoiceDetailsForInvoice()
        {
            InvoiceDB db = new InvoiceDB();
            Invoice i = db.Invoices.First();
            ((IObjectContextAdapter)db).ObjectContext.Detach(i); //http://stackoverflow.com/questions/4168073/entity-framework-code-first-no-detach-method-on-dbcontext
            Assert.NotNull(i);

            InvoiceDetailsController idc = new InvoiceDetailsController();
            System.Web.Mvc.PartialViewResult result = idc.IndexByInvoice(i.InvoiceID);

            Assert.IsInstanceOf(typeof(List<InvoiceDetails>), result.ViewData.Model);
        }