Digging the Development Dust for Refactorings

Software repositories are rich sources of information about the software development process. Mining the information stored in them has been shown to provide interesting insights into the history of the software development and evolution. Several different types of information have been extracted and analyzed from different points of view. However, these types of information have not been sufficiently cross-examined to understand how they might complement each other. In this paper, we present a systematic analysis of four aspects of the software repository of an open source project - source-code metrics, identifiers, return-on-investment estimates, and design differencing - to collect evidence about refactorings that may have happened during the project development. In the context of this case study, we comparatively examine how informative each piece of information is towards understanding the refactoring history of the project and how costly it is to obtain