Lecture Notes in Computer Science 3472

20 Model-Based Testing – A Glossary
Alexander Pretschner and Martin Leucker
Overview The idea of model-based testing is to compare the I/O behavior of a
valid behavior model to that of a system one wants to test (the system under
test, SUT). In order to do so, a few I/O traces of the model are fixed. Picking
“interesting” traces is a demanding task, and it is reflected in test purposes and
test case specifications. The input part of a test case is applied to the SUT, and
the output of the SUT is compared to the output of the model (this expected
output is part of the the test case).
Since models are abstractions, or simplifications, it may be necessary to
bridge the different levels of abstraction between the model and the SUT. Before
being applied to the SUT, the input part of the test case may have to be
concretized to its level of abstraction. Output of the SUT may well have to be
abstracted before being compared to the output of the test case (that is, output
of the model). Sometimes it is the case that the levels of abstraction are identical.
When considering real-time or continuous systems, then often it is not possible
to predict the exact values. Instead, small deviations (so-called jitter) may be
acceptable in both the time and the value domains. A test case then represents
a whole family of runs of the SUT.
Terminology
• Test case A test case is a structure of input and expected output behavior.
– The structure is a finite sequence in case of (quasi-)deterministic systems.
A test case then corresponds to one or many intended runs of the SUT,
which is a consequence of acceptable jitter in the time and value domains
(this is why we call these systems quasi-deterministic, or deterministic,
for short).
– It is tree-like (of possibly infinite branching but finite length) in case of
nondeterministic systems. As in the case of deterministic systems, each
path in the tree corresponds to one or many runs of the SUT because of
jitter.
• Test data Test data is the input part of a test case.
• Test suite A test suite is a set of test cases. The notion of a test suite may
comprise a set of execution conditions: assumptions on the environment, configuration
of the SUT, etc. Test suites may be infinite or even uncountable.
However, when tests are actually performed, only a finite amount of input
can obviously be applied.
• Test purpose A test purpose is a property one wants to test. Examples include
“conformance”, “statement coverage”, “invariant ψ”. These properties
can be expressed informally or formally. In general, they cannot directly be
used for testing a system because
M. Broy et al. (Eds.): Model-Based Testing of Reactive Systems, LNCS 3472, pp. 607-609, 2005.
© Springer-Verlag Berlin Heidelberg 2005