A comprehensive catalog of refactoring strategies to handle test smells in Java-based systems

Test smells, detrimental coding practices that hinder high-quality test code development, pose a significant challenge in software testing and maintenance. Software refactoring, traditionally a powerful approach for addressing code smells and improving software quality without changing functionality, often focuses on production code, leaving test code overlooked. Despite extensive research in test smell refactoring, understanding the efficacy of existing refactoring operations on test code quality remains limited. Investigating real-world developer refactoring practices is crucial to bridge this knowledge gap. In this study, we investigate refactorings performed by developers to address test smells, resulting in a comprehensive catalog of test smells and their corresponding test-specific refactorings. Two test-specific refactorings closely tied to JUnit5 and seven version-agnostic refactorings for various JUnit versions have been identified. While many of these test-specific refactorings are documented in the literature, this analysis unveils new test-specific refactorings aimed at dealing with the “Inappropriate Assertion” test smell. This research provides insights into the challenges faced by developers and prevailing practices for effectively refactoring test code, thereby enhancing software testing and maintenance.