A Line Based Approach for Bugspots


Code review is an important aspect of modern software development but time consuming. In 2011, Google proposed the Bugspots algorithm to help reviewers to focus on files that are more bug prone. The algorithm ranks the files based on the number of bug-fixes they received in the past, weighted by the age of the corresponding commit. A higher score equals more bug-fixes in recent times and indicates that there will be more bugs in that file. In this thesis we propose Linespots, a modified version of the Bugspots algorithm that ranks the individual lines of code instead of whole files. Linespots gathers information by scoring every line involved in a bug-fix commit. Using these scores, Linespots can either give a list of ranked lines as a result or instead project the individual line scores back to file scores, offering the same result format as Bugspots this way. An evaluation process was setup, comparing both kinds of Linespots’ results to the results of Bugspots using hit density and the area under the hit density curve (AUCEC) as metrics. Both were proposed by Rahman et al. [5] in their work that served as a foundation for Bugspots. The evaluation finds that the projected results are less consistent than the original Bugspots algorithm and do not improve the hit density or AUCEC. The line-based results have worse AUCEC values by design but could improve the hit density across all tested projects and most parameter configurations.

Hamburg University of Technology