Lecture Notes in Computer Science 3472

Part II
Testing of Labeled Transition Systems
This part of the book is concerned with the theory of model-based testing where
real systems are assumed to be modeled as labeled transition systems (and extensions
thereof). Labeled transition systems were proposed by Keller [Kel76]
and are widely used as underlying models for data-intensive systems (sequential
and concurrent programs) as well as hardware circuits. The starting point of this
form of model-based testing is a precise, unambiguous model description of the
system under test. Based on this formal specification, test generation algorithms
generate provably valid tests, i.e., tests that test what should be tested and no
more than that. These algorithms provide automatic, faster and less error-prone
test generation facilities. A sketch of the testing approach is given in Figure 9.
By hypothesis, it is assumed that for any implementation a model does exist.
This assumption allows for reasoning about implementations as if they were
formal objects. Consequently, it allows to express conformance – is the implementation
under test a correct implementation of the specification? – as a formal
relation, denoted imp, between models of implementations and specifications.
Such a relation is called an implementation relation (sometimes also called conformance
relation). An implementation i is said to be correct with respect to
specification s if and only if the model of i is related to s by the implementation
relation: model of (i) imps. Implementation relatiuons are typically preorder
relations, i.e., relations that are reflexive and transitive (but not necessarily
symmetric).
The behaviour of an implementation under test (IUT, for short) is investigated
by performing experiments on the implementation and observing the