Understanding Plug-in Test Suites from an Extensibility Perspective

Plug-in architectures enable developers to build extensible software products. Such products are assembled from plug-ins, and their functionality can be enriched by adding or configuring plug-ins. The plug-ins themselves consist also of multiple plug-ins, and offer dedicated points through which their functionality can be influenced. A well-known example of such an architecture is Eclipse, best known for its use to create a series of extensible IDEs. In order to test systems built from plug-ins developers use extensive automated test suites. Unfortunately, current testing tools offer little insight in which of the many possible combinations of plug-ins and plug-in configurations are actually tested. To remedy this problem, we propose three architectural views that provide an extensibility perspective on plug-in-based systems and their test suites. The views combine static and dynamic information on plug-in dependencies, extension initialization, and extension usage. The views are implemented in ETSE, the Eclipse Plug-in Test Suite Exploration tool. We evaluate the proposed views by analyzing eGit and Mylyn, two open source Eclipse plug-ins.