On the Influence of UML Class Diagrams Refactoring on Code Debt: A Family of Replicated Empirical Studies

Context: System modeling usually precedes coding activities during software development. Addressing model smells in the upfront can avoid their propagation to the source code. Technical debt (TD) affects several software development phases, including design, but little is still known about it at the modeling level. Goal: Investigate whether applying refactoring procedures in UML class diagrams improves the quality of the automatically generated code in terms of TD (code debt) reduction. Method: We perform three replications of an empirical study following the same protocol used in the original study, but with variations on the: (1) round- trip engineering tool, (2) code issue identification tool, and (3) analyzed class diagram. Each study considered two sets of refactoring tasks. The first applied successive model refactoring sessions in a class diagram and analyzed their resulting automatically generated code. The second applied successive code refactoring sessions and analyzed their resulting automatically generated model. Results: There is a weak relationship between the analyzed model smells and code issues. Round-trip engineering tools influence the presence of code issues. Lastly, code issues identification tools mostly consider code formatting problems, in detriment of design issues smells. Conclusion: Results confirm the findings of the original study and motivate further investigation on the correspondence between model smells and code issues to prevent code debt at the model level.