Large-Scale Enterprise Systems: Changes and Impacts

Changes and their impacts to large-scale enterprise systems are critical and hard to identify and calculate. This work focuses on analysing changes and their potential impacts, and in particular on how regression testing following such changes can be minimised. The target scope of the approach we describe here is systems containing hundreds of thousands of classes and millions of methods. It is extremely difficult and costly to apply regular regression testing techniques to such systems. It is very expensive and often unnecessary to retest everything after a change is introduced. Selective retesting is dangerous if the impacts of change are not understood, and analysing such systems to understand what is being changed and what the impacts are is difficult. This paper proposes a way to perform a change impact analysis which makes it possible to do efficient, targeted regression testing of enterprise systems. Our approach has been tried on a large system comprising 4.6 million methods with 10 million dependencies between them. Using our approach, maintainers can focus on a smaller, relevant subset of their test suites instead of doing testing blindly. We include a case study that illustrates the savings that can be attained.