Towards a Taxonomy of SUnit Tests

Although unit testing has gained popularity in recent years, the style and granularity of individual unit tests may vary wildly. This can make it difficult for a developer to understand which methods are tested by which tests, to what degree they are tested, what to take into account while refactoring code and tests, and to assess the value of an existing test. We have manually categorized the test base of an existing object-oriented system in order to derive a first taxonomy of unit tests. We have then developed some simple tools to semi-automatically categorize tests according to this taxonomy, and applied these tools to two case studies. As it turns out, the vast majority of unit tests focus on a single method, which should make it easier to associate tests more tightly to the methods under test. In this paper we motivate and present our taxonomy, we describe the results of our case studies, and we present our approach to semi-automatic unit test categorization