Test development for communication protocols: towards automation

In this paper we give an introduction to methods and tools for testing communication protocols and distributed systems. In this context, we try to answer the following questions: Why are we testing? What are we testing? Against what are we testing?... We present the different approaches of test automation and explain the industrial point of view (automatic test execution) and the research point of view (automatic test generation). The complete automation of the testing process requires the use of formal methods for providing a model of the required system behavior. We show the importance of modelling the aspects to be tested (the right model for the right problem!) and point out the different aspects of interest (control, data, time and communication). We present the problem of testing based on models, in the form of finite state machines (FSMs), extended FSMs, timed FSMs and communicating FSMs, and give an overview of the proposed solutions and their limitations. Finally, we present our own experience in automatic test generation based on SDL specifications, and discuss some related work and existing tools.