Specification for testing

The success of model-based testing, in automating the testing of an implementation given its state-based (or model-based) specification, raises the question of how best the specification can be tweaked in order to facilitate that process. This paper discusses several answers. Motivated by an example from web-based systems, and taking account of the restriction imposed by the testing interface, it considers both functional and non-functional properties. The former include laws, implicit system invariants and other consistency conditions whilst the latter include security leaks. It concludes that because of the importance of the link between specification and implementation in the testing process, there is a trade-off between genuinely useful testing information and the incorporation of some degree of information about the link, not normally regarded as part of the specification.