Do code reviews lead to fewer code smells?

Abstract

Context: The code review process is conducted by software teams with various motivations. Among other goals, code reviews act as a gatekeeper for software quality. Objective: In this study, we explore whether code reviews have an impact on one specific aspect of software quality, software maintainability. We further extend our investigation by analyzing whether code review process quality (as evidenced by the presence of code review process smells) influences software maintainability (as evidenced by the presence of code smells). Method: We investigate whether smells in the code review process are related to smells in the code that was reviewed by using correlation analysis. We augment our quantitative analysis with a focus group study to learn practitioners’ opinions. Results: Our investigations revealed that the level of code smells neither increases nor decreases in 8 out of 10 code reviews, regardless of the quality of the code review. Contrary to our own intuition and that of the practitioners in our focus groups, we found that code review process smells have little to no correlation with the level of code smells. We identified multiple potential reasons behind the counter-intuitive results based on our focus group data. Furthermore, practitioners still believe that code reviews are helpful in improving software maintainability. Conclusion: Our results imply that the community should update our goals for code review practices and reevaluate those practices to align them with more relevant and modern realities.