A Debugging and Testing Tool for Supporting Software Evolution

This paper describes a tool for debugging programs which develop faults after they have been modified or are ported to other computer systems. The tool enhances the traditional debugging approach by automating the comparison of data structures between two running programs. Using this technique, it is possible to use early versions of a program which are known to operate correctly to generate values for comparison with the new program under development. The tool allows the reference code and the program being developed to execute on different computer systems by using open distributed systems techniques. A data visualisation facility allows the user to view the differences in data structures. By using the data flow of the code, it is possible to locate faulty sections of code rapidly. An evaluation is performed by using three case studies to illustrate the power of the technique. The high cost of software development, in combination with advances in software engineering, has caused the emergence of a software development methodology based on evolution. In this methodology, new programs are built from existing ones, utilising sections of code from old program