The Impact on the Test Coverage Caused by the Introduction of Adaptive Behavior in a Legacy Web Application: A Case Study

Self-Adaptive systems (ASs) are an alternative to get IT professionals free from details of operation and maintenance. Web applications can incorporate characteristics of an AS in order to make them autonomous. However, one of the challenges of software engineering is to transform a legacy system into an AS. Furthermore, transforming a legacy system into an AS can lead to the insertion of faults. This way, the code coverage information produced by software tests assist in activities related to the evolutionary maintenance of the system. In this work, we analyzed, through the comparison of coverage metrics, how the introduction of adaptive behaviors in a real world legacy web application impacted on code coverage. For each implemented scenario, a set of test cases was created in the legacy version of the web application. Then, evolutionary versions were developed with the introduction of adaptive behavior. The versions (legacy and adaptive) were organized into branches of the version control system so that adaptive implementations have evolved in two technological ways. The coverage metrics for each version of the web application were collected to allow data analysis. Beyond the legacy version, we analyzed the coverage of six versions of the web application with adaptive behavior. The results indicate that the impact on the total code coverage is relevant, where even relatively small changes can considerably affect, either positively or negatively, the percentage of coverage of the changed unit.