An empirical study of the relationship between refactorings and merge conflicts in javascript repositories

Abstract

Maintenance activities are crucial to prolong the lifecycle of a software. An important ac tivity during software maintenance is refactoring, which is a transformation that improves the quality of the internal structure of the code without changing its behavior. During soft ware development, Version Control Systems (VCS) are used to integrate changes made by developers. These integration procedures, known as merge processes, may result in conicts if changes are made in the same place in the code. This work aims to analyze the possible relationship between refactorings and merge conicts in JavaScript code. We analyzed 76 JavaScript repositories, including 81,856 merge scenarios, which 6,356 of them have con- icts. We discovered a moderate positive correlation between the number of conicts les/- conicting regions and relationship/number of refactoring. For the second research question we found that the refactoring types Internal move, Move and Rename are more related to the conicting areas, as well as a moderate correlation between the number of conicts and the number of types of refactoring performed. 8 types of refactorings were identied at the conicting le level and also at the conict region level. Through statistical analysis, the relationship between the number of refactoring types and the number of conicts was the strongest found result in our study. In addition to our automatic analysis, a manual study was conducted that analyzed 535 evolutionary commits, verifying that 447 (84%) of these were classied as oss refactoring because they had other types of modications involved in the process. 88 evolutionary commits analyzed were classied as pure refactoring, representing 16% of evolutionary commits that only have refactoring actions.