NullReferenceException during unittesting Db connection

Question

I'm getting error like below:

An exception of type 'System.NullReferenceException' occurred in magazyn.dll but was not handled in user code

Additional information: Object reference not set to an instance of an object.

This error is thrown in this method:

public ActionResult Details(int? id)
    {
        if (id == null)
        {
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        }
        Storage storage = unitOfWork.storageRepository.GetByID(id.Value);
        if (storage == null)
        {
            return HttpNotFound();
        }
        return PartialView(storage);
    }

in this line:

Storage storage = unitOfWork.storageRepository.GetByID(id.Value);

Here my unit Test code:

[TestMethod]
public void Details()
{
    int? a = null;
    var result = SC.Details(a);
    Assert.IsInstanceOfType(result, typeof(HttpStatusCodeResult));
    var code = result as HttpStatusCodeResult;
    Assert.AreEqual((int)HttpStatusCode.BadRequest, code.StatusCode);
    a = 1;
    result = SC.Details(a);
    Assert.IsInstanceOfType(result, typeof(HttpNotFoundResult));
}

I tried debugging this test and all values are passed correctly. In db there is a record with Id=1 What is wrong with this code?

@Update with Test initialization:

 [TestInitialize]
    public void Initialize()
    {
        Mock<IUnitOfWork> mock = new Mock<IUnitOfWork>();
        fakeRepo = mock.Object;
        SC = new StorageController(fakeRepo);
    }

possible duplicate of What is a NullReferenceException and how do I fix it? — nvoigt
– nvoigt, Commented Mar 13, 2014 at 8:50

Alberto Solano · Accepted Answer · 2014-03-13 08:44:48Z

1

Check the objects and properties of this line:

Storage storage = unitOfWork.storageRepository.GetByID(id.Value);

Are you sure that unitOfWork is correctly initialized? What about storageRepository? Check both of them with the debugger, setting a breakpoint on this line.

answered Mar 13, 2014 at 8:44

Alberto Solano

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Comments

Aftab Ahmed · Accepted Answer · 2014-03-13 08:40:30Z

1

I think Your Object unitOfWork is null try to create an instance of this object

UnitOfWork unitOfWork=new UnitOfWork();

answered Mar 13, 2014 at 8:40

Aftab Ahmed

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2 Comments

szpic Over a year ago

I updated my code. UnitOfwork is OK. When I pass Id=null everything is ok and I get what I want and Assert pass. Problem is with Id!=null

Aftab Ahmed Over a year ago

try to make sure storageRepository has value other than null. i suspect when you pass id with some value storageRepository is throwing some exception and in turn it returns null.

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