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Model-Based Mutation Testing of
Hybrid Systems
Bernhard K. Aichernig, Harald Brandl, Elisabeth Jobstl, and Willibald Krenn
Institute for Software Technology, Graz University of Technology
{
aichernig,hbrandl,ejoebstl,wkrenn
}
@ist.tugraz.at
Abstract.
This paper presents a novel model-based testing approach
developed in the MOGENTES project. The aim is to test embedded
systems controlling a continuous environment, i.e., hybrid systems. We
present our two key abstractions against which we systematically test
for conformance. (1) Classical action systems are used to model the dis-
crete controller behavior. (2) Qualitative differential equations are used
to model the evolutions of the environment. The latter is based on a
technique from the domain of Artificial Intelligence called qualitative
reasoning. Mutation testing on these models is used to generate effec-
tive test cases. A test case generator has been developed that searches
for all test cases that would kill a mutant. The mutant models repre-
sent our fault models. The generated test cases are then executed on the
implementation in order to systematically exclude the possibility that a
mutant has been implemented.
1
Introduction
The EU FP7 project MOGENTES aims at significantly enhancing testing of
dependable embedded systems by means of automated generation of test cases.
As its full name Model-based Generation of Tests for Dependable Embedded
Systems indicates the approach to address this aim is model-based testing.
In model-based testing a (formal) model of the system under test (SUT) serves
two purposes, to generate the input stimuli and as a test oracle for the expected
behavior. Figure 1 gives the general picture. A tester produces a model and gen-
erates test cases from it. The tests are automatically executed. If all possible tests
pass, we have conformance between the model and the SUT. However, since ex-
haustive testing is impractical, we have to select a proper subset of possible test
cases. Hence, the aim is to show non-conformance, i.e., to find bugs in the SUT.
Since the project deals with highly critical systems, e.g., in the transportation
domain, the techniques have to be well-grounded. Therefore, a formal testing
approach is required implying, (1) models with precise semantics, (2) well-defined
notions of conformance, and (3) an explicit notion of fault models and coverage.
The latter is addressed by applying mutation testing techniques to the modeling
level.
Research herein was funded by the EU FP7 project ICT-216679, Model-based Gen-
eration of Tests for Dependable Embedded Systems (MOGENTES).
