Unit test NullReferenceException with string property problem

Question

I'm writing unit test for ASP.MVC 3 app with EF 4.0 and I have problem with System.NullReferenceException during the testing. I'm testing this method in service layer:

public IQueryable<Pricing> GetPricing(int categoryID)
    {
        var query = from t in _repository.GetAllPricing()
                    where t.FK_Category == categoryID
                    where t.Status.Equals("1")
                    select t;
        return query;
    }

It's working fine. But when Status equals to null and I call

svc.GetPricing(1).Count();

in the test method, then it throws exception. I'm using fake repository and other (empty) string works well.

I've tried to use pricing.Status = Convert.ToString(null); instead of pricing.Status = null; but this doesn work either.

Jackson Pope · Accepted Answer · 2011-04-04 19:52:09Z

1

The problem is that you can't call .Equals on a null reference - it will as you've experienced throw a NullReferenceException.

Instead you can call the equality operator:

public IQueryable<Pricing> GetPricing(int categoryID)
{
    var query = from t in _repository.GetAllPricing()
                where t.FK_Category == categoryID
                where t.Status == "1"
                select t;
    return query;
}

answered Apr 4, 2011 at 19:52

Jackson Pope

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2 Comments

xxviktor Over a year ago

Thank you, test pass now. So when use Equals and when ==? Application worked fine with Equals to, only tests fail.

Jackson Pope Over a year ago

variable.Equals(other) will work UNLESS variable is (or could be) null. I'd stick to == to be on the safe side.

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