Question

I have similar methods in the business layer. I am new to unit testing and sometimes get confused. For an idea, can you suggest, what will be a better approach to test this method
behaviour? I am using C# NUnit and Moq

public int? AddNewCatRetID(string categoryName)
{
  int? categoryID = 0;
  Adapter.AddNewBlogCategoryReturnID(categoryName, ref categoryID);

  if (categoryID.HasValue)
    return categoryID;

  return 0;
}

where

Adapter = Visual Studio 2008, Data Set Designer generated TableAdater

AddDeveloperCategoryReturnID() = Name of a function which utilises a Stored procedure in DB

It adds a new record, “Category” and returns its auto generated ID. If it is non zero, we take that result for further processing.

I know should not be interested in talking to Database, below is the procedure, just to give an idea about what is going on in DB

PROCEDURE [dbo].[AddDeveloperCategoryReturnID]

@NAME NVARCHAR(MAX),
@CATEGORY_ID INT OUTPUT
AS
 BEGIN
 INSERT INTO [AllTimeGreatProgrammersDateBase].dbo.CATEGORIES(NAME )
 VALUES (@NAME );

 SET @CATEGORY_ID = SCOPE_IDENTITY();

 SELECT @CATEGORY_ID;
END

some issues

• how to check the values returned using “ref” from the method
• what will you prefer to test and not to test? will be great if can list

Answer 1

I’d first convert Adapter.AddNewBlogCategoryReturnID(categoryName, ref categoryID) so that instead of returning a variable by reference, it simply returned the value.

Then, I would extract that into a virtual method.

To test AddNewCatRetID, I would extend the class to make a testable version, and override that virtual method to return an int? stored in a public variable.

That way, when you test to see what happens when you call AddNewCatRetID in a situation where there’s a 0 in the database, you don’t need to actually put a 0 in the database – you just set that parameter on the testable version of your class, and when your test calls AddNewCatRetID, instead if hitting the database, it just returns the value you set. Your test is guaranteed to be faster if you can avoid hitting the database, and since it’s MS’s generated adapter, there’s not really a need to test it – you only care about what your method does with what the adapter returns.