Lecture Notes in Computer Science 3472

Part III
Model-Based Test Case Generation
The previous parts of this book have, in general, been concerned with checking
models against models. A theoretical underpinning with, among other things,
respect to completeness of these approaches has been given.
If correctness of a model w.r.t. another model is to be proved, then the size of
their state spaces becomes a crucial problem. It may turn out that with today’s
technology, mathematical verification is not possible for arbitrary systems. In
addition to complexity issues, checking models against models—or properties—is
crucially dependent on the assumptions that have been encoded into the models.
Mathematically established correctness only holds under the condition that these
assumptions do indeed hold.
As a consequence, there is a growing agreement that verification technology
such as model checking or deductive theorem proving must hence be complemented
with activities that relate the real world to the models. This is particularly
true for embedded devices where complex systems interact with an equally
complex environment.
The idea of model-based testing is then to have a model of the system, or
specification, and use this model to generate sequences of input and expected
output. Roughly speaking, the input is applied to the system under test, and the
system’s output is compared to the model’s output, as given by the generated
trace. This implies that the model must be valid, i.e., that it faithfully represents
the requirements. The apparatus of the previous parts can be seen as a means
to increase confidence that a model does indeed conform to the requirements.