| M. Wetzel
| creator |
Wetzel, Matthias
| | date |
2004-03-09
| | | | description |
132 pages
| |
Software running on embedded systems is playing an increasingly
important role in safetycritical and mission-critical applications.
Formal documentation methods, like the Tabular Expressions invented
by Parnas et al., avoid the ambiguities inherent in natural language
by using mathematical notation. This allows the intended behavior of
software to be precisely defined, reducing the number of errors that
are caused by misleading documentation. Despite its shortcomings,
software testing is considered an important part of software quality
assurance. A fundamental assumption of software testing is the
existence of some mechanism, which is called an oracle, that is able
to determine whether the results of a test execution are correct.
The oracle is often implemented by manually deriving the expected
output from informal and possibly inconsistent documentation and
then comparing it to the actual test results. This procedure is both
time-consuming and error-prone. However, if a formal specification
exists, it can be used to automatically evaluate the test results
and determine the success or failure of a test execution. This
thesis describes the design and implementation of a working
prototype, which combines the use of Tabular Expressions and
embedded-systems products developed by Ashling Microsystems Ltd. in
a tool that is able to automatically execute function tests on a
target embedded system, and evaluate their results using an existing
formal specification of the tested function. In addition to
testresult-evaluation, the tool is able to determine the
specification-coverage of a given set of testcases on the basis of a
formal specification, without depending on knowledge or even
existence of program code. This allows measuring and improving test
quality at any phase of a software project, even prior to
implementation. A small trial application demonstrates the
usefulness of the methods described in this work. Possible
applications in projects and expected benefits are discussed. It is
shown that using tests based on formal documentation enforces
consistency between documentation and implementation, which greatly
increases the value of such a documentation, especially to
maintenance programmers. It is further argued that tools performing
such tests help to reduce costs for software testing while improving
test quality, and by doing so more than compensate the additional
costs of creating formal specifications.
| | format |
application/pdf
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