An Investigation on the Evolutionary Nature of Exception Handling Violations in Software Product Lines

The Exception Handling (EH) is a widely used mechanism for building robust systems and it is embedded in most of the mainstream programming languages. In the context of Software Product Lines (SPL), we can find exception handling code associated to common and variable features of an SPL. However, studies have shown that the exception handling code can also become a source of bugs which may affect the system the other way around, making it even less robust. This paper describes an empirical study whose goal was to investigate the evolutionary nature of exception handling violations. Can the exception handling behavior be preserved along SPL evolution scenarios? In order to carry out this study we extended a tool, called PLEA, which statically discovers the exception handling flows on SPLs (those implemented in Java and using annotation techniques), and it was executed over five to seven versions of two distinct SPLs. Our goal was to identify how the different kinds of evolution scenarios affected the exception handling policy initially defined. The results showed that the evolution of the SPLs exception handling code did not occur in a planned way in most of the scenarios. Consequently, it led to violations on the exception handling behavior. This paper points out the need of a set of EH behavior-preserving evolution scenarios for the SPLs exception handling code.