A Metric Based Evaluation of Unit Tests as Specialized Clients in Refactoring

Abstract

In the context of refactoring, a unit test significantly differs from an ordinary client. A unit test is the only safety net available to verify the impact of refactoring. In addition, tight coupling and stronger association with the refactored class are its key discriminating characteristics. Hence, any change in the code readily affects the behavior and quality of the test code. But if test code is adapted and refactored along the production code, its behavior shall be preserved and quality may improve. In this paper with the help of quality metrics, we establish the fact that unit test is a different type of client that needs “special“ handling in the context of refactoring. We demonstrate through most commonly used refactorings on an open source project that there is a need to enhance the existing refactoring support for Java to include the specific adaptation mechanism for unit tests that eradicates the effect of refactoring and also improves the internal structure of test code.