Unit Testing a Private Method using NUnit

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First rule of thumb: Don't do this.

No really, Don't.

You are locking the internals of your code down with your unit test, if you are having to test a private method, then chances are that method should be public on a different class.

However, if you are sitting in a situation where that kind of refactoring is just not going to be allowed and you still really-really-need-to-get-this-under-test, then this simple process can help.



Given

Private Function Add2Integers(byval x as integer, byval y as integer) as integer

return x + y

End Function



You want to get this under test, but you want this to be a refactor (which is NOT another word for maintenance, it's a word for code clean up, not feature changing) which means no changes as far as the users are concerned.



Try this, wrap the code in a compiler conditional, and then just call the function, and then pass the value back out.

Now your unit tests can access the private method.

#If DEBUG (or something else if you have another compiler conditional) Then

Public Function public_Add2Integers(byval x as integer, byval y as integer) as integer

return Add2Integers( x, y) as integer

End Function