Issues in Testing Collection Class Libraries

Collections or containers have become a standard facility used by almost any software application. The availability and widespread use of collection class libraries, the large number of systems depending on them, their algorithmic complexity, as well as their object-oriented design demand an elaborated testing approach. Despite the availability of such testing approaches, many industry projects still rely on unstructured unit testing without particular test criteria applied. In this paper we highlight issues involved in testing collection class libraries and report preliminary results from a pilot study on ad-hoc unit testing of collection classes. We show that a reasonable number of defects can be found in a short period of time that higher coverage does not necessarily lead to a larger number of defects found, and report on three distinct strategies used for writing test cases. Still some questions remain and could be discuss in the workshop.