Empirical Evaluation of the Impact of Object-Oriented Code Refactoring on Quality Attributes: A Systematic Literature Review

Software refactoring is a maintenance task that addresses code restructuring to improve its quality. Many studies have addressed the impact of different refactoring scenarios on software quality. This study presents a systematic literature review that aggregates, summarizes, and discusses the results of 76 relevant primary studies (PSs) concerning the impact of refactoring on several internal and external quality attributes. The included PSs were selected using inclusion and exclusion criteria applied to relevant articles published before the end of 2015. We analyzed the PSs based on a set of classification criteria, including software quality attributes and measures, refactoring scenarios, evaluation approaches, datasets, and impact results. We followed the vote-counting approach to determine the level of consistency among the PS reported results concerning the relationship between refactoring and software quality. The results indicated that different refactoring scenarios sometimes have opposite impacts on different quality attributes. Therefore, it is false that refactoring always improves all software quality aspects. The vote-counting study provided a clear view of the impacts of some individual refactoring scenarios on some internal quality attributes such as cohesion, coupling, complexity, inheritance, and size, but failed to identify their impacts on external and other internal quality attributes due to insufficient findings.