Got NullReferenceException when Unit testing Controller

Question

I am working on Unit testing the MVC3 site using NUnit, MvcContrib.TestHelper package but I am facing the exception "Object reference not set to an instance of an object" when my test method accesses the controller having TryUpdateModel. I dont know what to do to pass the test. please help me in this.

I am also giving a code for that :

Action from Controller which test method calls, is given below :

public JsonResult AddPatient()
    {
         bool returnStatus;
        string returnErrorMessage;

        List<string> returnMessage;

        PatientBLL patientBLL = new PatientBLL();

        Models.PatientViewModel patientViewModel = new Models.PatientViewModel();          

        TryUpdateModel(patientViewModel);

        Patient patient = patientBLL.AddPatient(
            patientViewModel, 
            out returnMessage, 
            out returnStatus, 
            out returnErrorMessage);

        patientViewModel.UpdateViewModel(patient, typeof(Patient).GetProperties());

        patientViewModel.ReturnMessage = returnMessage;
        patientViewModel.ReturnStatus = returnStatus;

        return Json(patientViewModel);

    }

and the test method which calls the above action is given below :

[Test]
    public void Test_AddPatient()
    {
        TestControllerBuilder builder = new TestControllerBuilder();

        string uniquePatientKey = GenerateUniqueID();

        builder.Form["MedicalID"] = uniquePatientKey;
        builder.Form["SocialSecurityNumber"] = uniquePatientKey;
        builder.Form["FirstName"] = "Khushi";
        builder.Form["LastName"] = "Maahi";
        builder.Form["AddressLine1"] = "ABCD";
        builder.Form["AddressLine2"] = "Technologies";
        builder.Form["City"] = "OOna";
        builder.Form["State"] = "UP";
        builder.Form["ZipCode"] = "98456-7329";
        builder.Form["PhoneNumber"] = "(425)882-8080";
        builder.Form["DateOfBirth"] = "10/28/1987";
        builder.Form["PatientDateOfBirth"] = "10/28/1987";
        builder.Form["EffectiveDate"] = "01/01/1995";
        builder.Form["PatientEffectiveDate"] = "01/01/1995";

        PatientController patientController = builder.CreateController<PatientController>();
       JsonResult jsonResult = (JsonResult)patientController.AddPatient();

        dynamic jsonData = jsonResult.Data;
        string jsonMessage=Convert.ToString(jsonData.ReturnMessage);
        Assert.AreEqual(jsonData.ReturnStatus, true );
        Assert.Greater(jsonData.PatientID, 0);


    }

Please give me the solution for my probelm.

Answer 1

You have a null somewhere in patientViewModel. Can you post that type here? This could be a problem with mixing models and view models.