Lecture Notes in Computer Science 3472

402 Axel Belinfante, Lars Frantzen, and Christian Schallhart
Summary
Lurette is targeted at the fully automated testing of synchronous reactive systems.
It builds a test harness from an environment description, a SUT, and an
oracle. The SUT and the oracle must be given in terms of a C-file which implement
a specific set of procedures. The environment description must be given
in Lustre. It describes the environment and the test purpose simultaneously.
The generated test sequence is chosen randomly such that relevance and interest
constraints are satisfied.
Lurette allows to test SUTs which have numerical inputs and outputs. However,
Lurette is only able to deal with linear constraints between these numerical
parameters. Each step in the test sequence generation is subdivided into two
phases, first an abstracted environment description is used to obtain a set of
linear constraints to be satisfied. Then the obtained constraint set is solved.
On the other hand, Lurette is not able to deal with liveness properties and
it only allows to specify test purposes in terms of safety properties.
14.2.3 GATeL
Introduction
The third Lustre-based tool which is described here is GATeL 5 [MA00]. Its
approach is quite different from the two other Lustre related tools (Lutess and
Lurette) presented in this chapter. Lutess and Lurette start the test sequence
generation from the initial state. Then the sequence is generated on the fly, i.e.,
in each step the outputs of the SUT are used to compute a new input for the SUT
based on the environment description and the test purpose. This process is iterated
either until a negative test verdict is produced, or until the maximum test
sequence length is reached. In contrast, GATeL starts with a set of constraints
on the last state of the test sequence to be generated. This set of constraints can
contain invariant properties as well as any other constraint on the past which can
be expressed in Lustre. The latter amounts to a test purpose since it allows to
state a predicate on all sequences which are of interest. During the test sequence
generation, GATeL tries to find a sequence which satisfies both, the invariant
and the test purpose. To find such a sequence, GATeL employs constraint logic
programming (CLP) in a search process which extends the sequence backwards,
i.e., from the last state to the first one.
Testing Method
GATeL requires the SUT or a complete specification of the SUT, an environment
description, and a test objective. All three elements must be supplied as Lustre
source code. All three components of the test harness are not allowed to use real
variables or tuples.
5 See also http://www-drt.cea.fr/Pages/List/lse/LSL/Gatel/index.html.