Unit testing, Exercise Stack

Hi, using the example code from the Unit test exercise, I am unable to get this to throw an exception no matter what I do.

    public void Push_NotNull_ThrowException()
       var stack = new Stack<string>();
        Assert.That(() => stack.Push(null), Throws.TypeOf<ArgumentNullException>());

Is this an environment issue as I am using the same Version of NUnit as Mosh here?

Below is the result of the test.

Expected: <System.ArgumentNullException>
But was: no exception thrown

Stack Trace:
StackTests.Push_NotNull_ThrowException() line 18

I will answer this now that I have figured out the error of my ways here, I did not reference Fundamentals.Stack :frowning :flushed:

Just incase someone else makes the same sill mistake.

Well, I think there are some logical issues with your code.
Please try this code once.

public class Stack<T>
    private List<T> items = new List<T>();

    public void Push(T item)
        if (item == null)
            throw new ArgumentNullException(nameof(item), "Item cannot be null.");

I hope this code will fix your error.

Excellent advice thank you gulshan212

1 Like

What does the T stands for?
Thank you!


I am pretty new to nUnit myself but I am using it daily for the last 2 weeks at work.

Try to use Assert.Throws instead.

As for the T part it belongs to generic programming.

Basically instead of doing the same code for different types you use a generic parameter to represent a type. You can also add constraints to tell what is allowed or not to be a T.