Deursen. Mining software repositories to study co-evolution of production and test code

Engineering software systems is a multidisciplinary ac-tivity, whereby a number of artifacts must be created — and maintained — synchronously. In this paper we investigate whether production code and the accompanying tests co-evolve by exploring a project’s versioning system, code cov-erage reports and size-metrics. Our main aim for studying this co-evolution is to create awareness with developers and managers alike about the testing process that is followed. We explore the possibilities of our technique through two open source case studies and observe a number of different co-evolution scenarios. We evaluate our results both with the help of log-messages and the original developers of the software system.