Towards Better Understanding of Software Quality Evolution through Commit-Impact Analysis

Developers intend to improve the quality of the software as it evolves. However, as software becomes larger and more complex, those intended actions may lead to unintended consequences. Analyzing change in software quality among different releases overlooks fine-grained changes that each commit introduces. We believe that studying software quality before and after each commit (commit-impact analysis) can reveal a wealth of information about how the software evolves and how each change impacts its quality. In this paper, we explore whether each commit has an impact on the source code, investigate the compilability of each impactful commit, examine how source code changes affect software quality metrics, and study the effectiveness of using a certain metric as software quality indicator. We analyze a total of 19,580 commits from 38 Apache Java software systems to better understand how change occurs, why, and by who.