Model-based testing of automotive HMIs with consideration for product variability

The human-machine interfaces (HMIs) of today’s premium automotive
infotainment systems are complex embedded systems which have
special characteristics in comparison to GUIs of standard PC
applications, in particular regarding their variability. The
variability of infotainment system HMIs results from different car
models, product series, markets, equipment configuration
possibilities, system types and languages and necessitates enormous
testing efforts. The model-based testing approach is a promising
solution for reducing testing efforts and increasing test coverage.
However, while model-based testing has been widely used for
function tests of subsystems in practice, HMI tests have remained
manual or only semi-automated and are very time-consuming and
work-intensive. Also, it is very difficult to achieve systematic or
high test coverage via manual tests. A large amount of research
work has addressed GUI testing in recent years. In addition,
variability is becoming an ever more popular topic in the domain of
software product line development. However, a model-based testing
approach for complex HMIs which also considers variability is still
lacking. This thesis presents a model-based testing approach for
infotainment system HMIs with the particular aim of resolving the
variability problem. Furthermore, the thesis provides a foundation
for future standards of HMI testing in practice. The proposed
approach is based on a model-based HMI testing framework which
includes two essential components: a test-oriented HMI
specification and a test generation component. The test-oriented
HMI specification has a layered structure and is suited to
specifying data which is required for testing different features of
the HMI. Both the dynamic behavior and the representation of the
HMI are the testing focuses of this thesis. The test generation
component automatically generates tests from the test-oriented HMI
specification. Furthermore, the framework can be extended in order
to automatically execute the generated tests. Generated tests must
first be initialized, which means that they are enhanced with
concrete user input data. Afterwards, initialized tests can be
automatically executed with the help of a test execution tool which
must be extended into the testing framework. In this thesis, it is
proposed to specify and test different HMI-variants which have a
large set of commonalities based on the software product line
approach. This means the test-oriented HMI specification is
extended in order to describe the commonalities and variabilities
between HMI variants of an HMI product line. In particular,
strategies are developed in order to generate tests for different
HMI products. One special feature is that redundancies are avoided
both for the test generation and the execution processes. This is
especially important for the industrial practice due to limited
test resources. Modeling and testing variability of automotive HMIs
make up the main research contributions of this thesis. We hope
that the results presented in this thesis will offer GUI testing
research a solution for model-based testing of multi-variant HMIs
and provide the automotive industry with a foundation for future
HMI testing standards.