[Reproduction package] Test Code Refactoring: A Literature Review and Classification of Refactoring Operations

Abstract: Test code refactoring is a crucial activity in software development that aims to maintain the quality of test code and, consequently, software products. Although several approaches and tools have been proposed to tackle test code refactoring, a synthesis of existing work is lacking. This paper presents the findings of a systematic literature review on test code refactoring, covering anti-patterns, refactoring strategies, and tools. The review analyzed 42 primary studies and identified 190 test code problems. The majority of the studies presented generic refactorings suitable for both production and test code, while few studies focused exclusively on test code design. Some anti-patterns had multiple refactoring strategies, while others lacked a clear strategy. Existing tools have not evolved significantly since their inception, and many refactoring strategies have not been evaluated. This study highlights the need for more studies on recommending refactorings for test code and investigating the effectiveness and effects of each refactoring approach. The results can guide future research on test code refactoring, providing direction for new refactorings and tools to improve the quality of software products.