A Practical Guide to Testing Object-Oriented Software

Subclass Test Requirements

Implementing classes is more straightforward when done from the top of the hierarchy down. In the same way, testing classes in an inheritance hierarchy is generally more straightforward when approached from the top down. In testing first at the top of a hierarchy, we can address the common interface and code and then specialize the test driver code for each subclass. Implementing inheritance hierarchies from the bottom up can require significant refactoring of common code into a new superclass. The same thing can happen to test drivers. To keep our discussion simpler, we will assume that the classes in an inheritance hierarchy are to be tested top down. First, we will focus on testing a subclass of a class that has ...