Test generation algorithms based on preorder relations

Abstract

Five test generation methods for LTSs have been presented in this chapter. This is certainly not an exhaustive presentation. A lot more methods exist. The first two methods have been chosen because they make an interesting link between FSM testing and LTS testing. These methods take advantage of former works concerning FSM and explain how to apply the FSM recipes to the LTS world. A drawback of this approach is that the conformance relation considered is the FSM (trace or testing) equivalence and not conf, the "standard" conformance relation in the LTS world. The other three methods presented in this chapter are well-known methods. The goal of each of them is the construction of a canonical tester. The method presented in Section 6.4.1 is compositional but limited to processes having a certain form. The CO-OP method removes this limitation. Finally, the method based on refusal graphs takes a different approach and allows us to construct automatically simplified (contrary to other methods) canonical testers. The main drawback is that, from a practical point of view, none of these methods is very useful. In fact, they can hardly be applied to realistic systems with many states and transitions. At best, they are limited to an academic use in academic tools. For instance, the CO-OP method has been implemented in a tool called Cooper (see 14.2.9 for further details). In order to tackle realistic systems, we need more realistic models (that differentiate inputs and outputs for instance) and methods that allow to handle huge (even infinite) systems. The next chapter will give you a picture of such methods. © Springer-Verlag Berlin Heidelberg 2005.