Does code review really remove coding convention violations?

Many software developers perceive technical debt as the biggest problems in their projects. They also perceive code reviews as the most important process to increase code quality. As inconsistent coding style is one source of technical debt, it is no surprise that coding convention violations can lead to patch rejection during code review. However, as most research has focused on developer’s perception, it is not clear whether code reviews actually prevent the introduction of coding convention violations and the corresponding technical debt.Therefore, we investigated how coding convention violations are introduced, addressed, and removed during code review by developers. To do this, we analysed 16,442 code review requests from four projects of the Eclipse community for the introduction of convention violations. Our result shows that convention violations accumulate as code size increases despite changes being reviewed. We also manually investigated 1,268 code review requests in which convention violations disappear and observed that only a minority of them have been removed because a convention violation has been flagged in a review comment. The investigation results also highlight that one can speed up the code review process by adopting tools for code convention violation detection.