How to Test the Extract Method Refactoring

ABSTRACTExtract Method is probably the most commonly used refactoring. Although it may seem quite simple at a first glance, there are many cases that it can become fairly complex. Local variables and parameters can make this refactoring difficult to implement. The whole procedure can also become quite error-prone. The only way to be sure that we performed the refactoring without introducing bugs is by means of testing. Testing, however, seems to many application developers a very bothersome procedure. To facilitate their work we discuss patterns that customize existing testing techniques to the specificities of the Extract Method refactoring.