Chen, Tse and Chen’s paper addresses a new methodology for testing called testing at the class and cluster levels (TACCLE). They provide an interesting insight into object-oriented testing. They detail a method for testing the interactions between related objects properties and methods, what they call a cluster. A specification language called Contract is used to describe the interactions between objects.

The introduction gives a brief background into what testing at the cluster level is. It also mentions some of the problems with other research that has been done in this area.

The paper then briefly describes testing using fundamental equivalent pairs. For more information on this subject, the reader is directed to other research done by Chen et al.

The main focus of this paper is on testing using nonequivalent terms. It goes into great detail describing how the TACCLE methodology can be used. Several examples are given to illustrate the concepts.

The paper is well written. It has a blend of technical information with a lot of easy-to-follow examples. It has simple implementation examples (a stack, a queue, and bank accounts) that make it easy to follow the points that are being made.

The purpose of this work is to continue research in the field of software testing, with an emphasis on object-oriented testing. This work is intended for anyone who is conducting research in this field. The ideas in the paper are helpful in generating test cases for software. A background in computer science is necessary to understand the algebraic specifications.