Question

Let’s say, I have this class

public class MyClass
{
   public int MyMethod(int? i)
   {
       throw new NotImplementedException();
   }
}

I have also a test class

[TestClass]
public class MyClassTest
{
  Public void Retur_Int_Greater_Than_Zero_When_Input_Is_Not_Null_And_Zero_Otherwise()
  {
     // Arrange
     var myVar = new MyClass();
     int? i = 3;

    // Act
    var result = myVar.MyMethod(i)  

   //Assert
   //
  } 
}

I’d like to check – if the input is null or 0, the result must be 0 – if the input is not null nor 0, the result must the absolute value of that number.

How do I express those assertions?

Can I write something like:

if(i.HasValue)
{
  //Define the Assert statement inside a If, else constructions...
}

Thanks for helping

Answer 1

You will need to create three tests instead of one to test three different scenarios

If the input is null or 0, the result must be 0

// Act
var result = myVar.MyMethod(null)  
//Assert
Assert.That(result, Is.EqualTo(0));

// Act
var result = myVar.MyMethod(0)  
//Assert
Assert.That(result, Is.EqualTo(0));

If the input is not null nor 0, the result must the absolute value of that number.

// Act
int graterThatZero = 1;
int absoluteValue = //define it here;
var result = myVar.MyMethod(graterThatZero)  
//Assert
Assert.That(result, Is.EqualTo(absoluteValue));

The same using TestCase attribute from NUnit

[TestCase(null,0)]
[TestCase(0,0)]
[TestCase(1, 1 /* absolute value */)]
[TestCase(-1, 1)]
public void MyMethod_should_return_absolute_value(int? argument, int expectedResult)
{
   // Arrange
   var myVar = new MyClass();
   // Act
   var result = myVar.MyMethod(argument) 
   // Assert
   Assert.That(result, Is.EqualTo(expectedResult));
}