Object reference error in unit testing - asp.net-mvc-3

Question

i have a controller action
[HttpPost]
public ActionResult CreateFocus(FocusFormModel focus)
{
var errors = focusService.CanAddFocus(Mapper.Map<FocusFormModel, Focus>(focus)).ToList();
ModelState.AddModelErrors(errors);
if (ModelState.IsValid)
{
focusService.CreateFocus(Mapper.Map<FocusFormModel, Focus>(focus));
var createdfocus = focusService.GetFocus(focus.FocusName);
return RedirectToAction("Focus", new { id = createdfocus.FocusId });
}
return View("CreateFocus", focus);
}
This action is working fine but when i am writing unit test it is showing error
Object Reference Not set to an instance of an object
the uni test is
[Test]
public void Create_Focus()
{
// Arrange
GroupController controller = new GroupController(groupService);
// Act
FocusFormModel focus = new FocusFormModel();
focus.GroupId = 1;
focus.FocusName = "t";
focus.Description = "t";
Mapper.CreateMap<FocusFormModel, Focus>().ForAllMembers(opt => opt.Ignore());
Mapper.AssertConfigurationIsValid();
var result = (RedirectToRouteResult)controller.CreateFocus(focus);
Assert.AreEqual("Index", result.RouteValues["action"]);
}
My Model is described below
public class Focus
{
public int FocusId { get; set; }
[StringLength(50)]
public string FocusName { get; set; }
[StringLength(100)]
public string Description { get; set; }
public int GroupId { get; set; }
public virtual Group Group { get; set; }
public DateTime CreatedDate { get; set; }
public Focus()
{
CreatedDate = DateTime.Now;
}
}
and i am writing my view model as
public class FocusFormModel
{
public int FocusId { get; set; }
[Required(ErrorMessage = "*")]
[StringLength(50)]
public string FocusName { get; set; }
[Required(ErrorMessage = "*")]
[StringLength(100)]
public string Description { get; set; }
public int GroupId { get; set; }
public virtual Group Group { get; set; }
public DateTime CreatedDate { get; set; }
public FocusFormModel()
{
CreatedDate = DateTime.Now;
}
}
Can any one please help me

Answer 1

This line actually provides 2 chances to get null reference exception:
var errors = focusService.CanAddFocus(Mapper.Map<FocusFormModel, Focus>(focus)).ToList();
first of all focusService might be null
if focusService is not null then method call CanAddFocus(Mapper.Map<FocusFormModel, Focus>(focus)) might return null
That are just assumptions.
As Greg Smith said stack trace would be very helpful here.