An empirical study of sentiments in code reviews

Context Modern code reviews are supported by tools to enhance developers' interactions allowing contributors to submit their opinions for each committed change in form of comments. Although the comments are aimed at discussing potential technical issues, the text might enclose harmful sentiments that could erode the benefits of suggested changes. Objective: In this paper, we study empirically the impact of sentiment embodied within developers' comments on the time and outcome of the code review process. Method: Based on historical data of four long-lived Open Source Software (OSS) projects from a code review system we investigate whether perceived sentiments have any impact on the interval time of code changes acceptance. Results: We found that (1) contributors frequently express positive and negative sentiments during code review activities; (2) the expressed sentiments differ among the contributors depending on their position within the social network of the reviewers (e.g., core vs peripheral contributors); (3) the sentiments expressed by contributors tend to be neutral as they progress from the status of newcomer in an OSS project to the status of core team contributors; (4) the reviews with negative comments on average took more time to complete than the reviews with positive/neutral comments, and (5) the reviews with controversial comments took significantly longer time in one project. Conclusion: Through this work, we provide evidences that text-based sentiments have an impact on the duration of the code review process as well as the acceptance or rejection of the suggested changes.