xUnit Testing says System.NullReferenceException

Question

Good day,

I'm begginer in xUnit and I'm facing this error that says, "System.NullReferenceException : Object reference not set to an instance of an object."

Here's my code where it tests whether a rulename depending on the season.

public class UnitTest1
{
    private CalculateDiscount calculateDiscount;

    [Fact]
    public void Setup()
    {
        calculateDiscount = new CalculateDiscount();
    }

    [Theory]
    [InlineData(10.00, "Summer", 100.00)]
    public void WhenRuleName_Is_Summer_Return_Valid(decimal amount, string ruleName, decimal expected)
    {
        var result = calculateDiscount.CalculateDiscountSalary(amount, ruleName);

        Assert.Equal(expected, result);
    }
}

And here is my actual implementation

public class CalculateDiscount
{
    public decimal CalculateDiscountSalary(decimal amount, string ruleName)
    {
        if (ruleName.Equals("Summer"))
        {
            return amount * 10.00M;
        }
        else if (ruleName.Equals("Winter"))
        {
            return amount * 15.00M;
        }
        else
        {
            return amount * 20.00M;
        }
    }
}

Thank you in advance.

Where is the error being thrown. I already know but want to see if you can learn how to debug from this process. What have you tried so far in trying to solve your problem? — Nkosi, Mar 27 '18 at 05:41
In the test method itself. The `WhenRuleName_Is_Summer_Return_Valid` sir — jsonGPPD, Mar 27 '18 at 05:42
Great, and what could possibly be null in that method? and why? Learn to step through your code. — Nkosi, Mar 27 '18 at 05:43
I'm trying to put a breakpoint on the `{` of this method but it doesn't break sir — jsonGPPD, Mar 27 '18 at 05:45
Oh I use the `Debug Selected Test` sir but the `calculateDiscount` is null. All the parameters have a value though — jsonGPPD, Mar 27 '18 at 05:50
When the break point hits, check the state of the variables at that point — Nkosi, Mar 27 '18 at 05:51
That is correct. Now why would it be null based on what you have in the test? — Nkosi, Mar 27 '18 at 05:52
Thank you sir. I just needed to put in on my constructor instead — jsonGPPD, Mar 27 '18 at 05:56
Possible duplicate of [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Maximilian Ast, Mar 27 '18 at 06:32

score 1 · Accepted Answer · answered Mar 27 '18 at 05:52

1

Fact do not have to run before Theory.

Your setup must be your constructor. If you change your setup function as constructor, your null reference exception problem is resolved

public UnitTest1()
{
    calculateDiscount = new CalculateDiscount();
}

answered Mar 27 '18 at 05:52

Adem Catamak

1,987
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score 0 · Answer 2 · answered Mar 27 '18 at 05:54

0

I guess you are confused with XUnit and NUnit.

NUnit provides a SetUp Fixture to initialize variables that you can use repeatedly.

As of the moment, XUnit doesn't have. But there are workarounds.

answered Mar 27 '18 at 05:54

KaeL

3,639
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xUnit Testing says System.NullReferenceException

2 Answers2