Graph-based visualization of merge requests for code review

Code review is a software development practice aimed at assessing code quality, finding defects, and sharing knowledge among developers. Despite its wide adoption, code review is a challenging task for developers, who often struggle to understand the content of a review change-set. Visualization techniques represent a promising approach to support reviewers. In this paper we present a new visualization approach that displays classes and methods in review changes as nodes in a graph. Then, we implemented our graph-based approach in a tool (ReviewVis) and performed a two-step feedback collection phase to assess the developers’ perceptions on the tool’s benefits through (1) an in-company study with nine professional software developers and (2) an online survey with 37 participants. Given the positive results obtained by this first evaluation, we performed a second survey with 31 participants with a specific focus on supporting developers’ understanding of a review change-set.