Unit Testing Abstract Class

Hello,

I have an abstract class and I need to do unit Testing on it... The problem is I can't create object of that class to test it...like constructor and some methods.

For the purpose of the unit testing do I need to make it not Abstract and when I'm done with my testing it goes back to an abstract Class?

Thanks!

No. If you have to modify a class before and after unit testing, you defeat the purpose of unit testing by allowing false passes (e.g. an error may be negated by modifying the class, so it passes the test, and then the error is re-applied after testing).


The more usual approach is to do unit testing (on instances of) all the concrete derived classes that takes account of all requirements supported by the base class.

Sometimes, it may be helpful to create a minimal concrete class for the specific purpose of unit testing (so, if that concrete pass passes unit testing, you deem the abstract class has passed as well). That requires some documented analysis to support the claim of "if this derived class passes unit testing so does the base class". It also potentially allows you to limit the scope of unit testing on other derived classes to concerns specific to those derived classes. The problem with this approach is that the "minimal concrete class for unit testing" should probably not be used in production code, and may conflict with other system requirements (e.g. absence of dead code).