On the Effect of Aspect-Oriented Refactoring on Testability of Classes: A Case Study

This paper aims at investigating empirically the effect of aspect-oriented refactoring on testability of classes in object-oriented software. We investigate testability from the perspective of unit testing. We performed an empirical analysis using (test suites and refactoring) data collected from a well-known open source Java software system (JHotdraw). We used, in fact, two versions of JHotDraw: the Java version (before aspect-oriented refactoring) and the AspectJ version (after aspect-oriented refactoring). To capture testability of classes, we used two metrics to quantify the corresponding JUnit test cases. JUnit test cases have been generated using a tool (CodePro). We also used object-oriented metrics to measure various source code attributes (coupling, cohesion, inheritance, complexity and size). In order to investigate the effect of aspect-oriented refactoring on testability of classes (characteristics of corresponding test cases), we used statistical tests. Results provide evidence that testability of the refactored classes has been improved.