Abstract: In this paper we describe our taxonomy of object-oriented classes that catalogs each class in an application based on the characteristics of that class. We present a mapping algorithm that matches the class under test to a list of implementation-based testing techniques, providing feedback to the tester describing the characteristics of the class that are suitably tested by each testing technique together with the characteristics that are not suitably tested by any of the testing techniques in the list. Our study shows that the number of entities to be analyzed by a tester when selecting implementation-based testing techniques can be reduced by 50 if the class under test is first cataloged using our taxonomy of OO classes.