Understanding Code Snippets in Code Reviews: A Preliminary Study of the OpenStack Community

TL;DR

This study investigates the use and purpose of code snippets in OpenStack community code reviews, revealing their limited prevalence, common purposes, and acceptance rates, thus providing insights for improving review practices.

Contribution

It offers the first detailed analysis of code snippets in open-source code reviews, identifying their purposes and acceptance, which informs future review process improvements.

Findings

Code snippets are not frequently used in reviews.

Most code snippets are provided by reviewers.

Approximately 68.1% of suggestion snippets are accepted by developers.

Abstract

Code review is a mature practice for software quality assurance in software development with which reviewers check the code that has been committed by developers, and verify the quality of code. During the code review discussions, reviewers and developers might use code snippets to provide necessary information (e.g., suggestions or explanations). However, little is known about the intentions and impacts of code snippets in code reviews. To this end, we conducted a preliminary study to investigate the nature of code snippets and their purposes in code reviews. We manually collected and checked 10,790 review comments from the Nova and Neutron projects of the OpenStack community, and finally obtained 626 review comments that contain code snippets for further analysis. The results show that: (1) code snippets are not prevalently used in code reviews, and most of the code snippets are provided by reviewers. (2) We identified two high-level purposes of code snippets provided by reviewers (i.e., Suggestion and Citation) with six detailed purposes, among which, Improving Code Implementation is the most common purpose. (3) For the code snippets in code reviews with the aim of suggestion, around 68.1% was accepted by developers. The results highlight promising research directions on using code snippets in code reviews.