Lecture Notes in Computer Science 3472

14 Tools for Test Case Generation 401
vertices and random selection within the polyhedron. The assignments to the
Boolean and numerical variables obtained by this procedure are used as input
vector to the SUT.
An Optimization Lurette does not only test linear test sequences. In each step
of a test sequence generation and execution, Lurette tests several inputs with
the SUT. More precisely, it computes the output of the SUT for a whole set
of input vectors and checks whether each of the correspondingly continued test
sequences would be correct. This is possible, since the SUT is required to provide
one method to produce the next output of the SUT without changing its state,
and a separate method to advance the state of the SUT. If an error is found, the
test sequence which provoked the error is returned along with a fail verdict and
Lurette terminates. If no error is detected, then the test sequence is continued
with one of the tested inputs. This is possible, since Lurette is requiring the SUT
to be given in a way that allows to compute the output of the SUT on a given
input vector without advancing its internal state.
SUT Program Format
To test a program with Lurette, this program must be given as a C-file which
implements a synchronous reactive program. In particular, the C-file must implement
a specific interface to be integrated into the test harness. This interface
must allow to access the following elements:
• The names and types of the inputs and outputs of the SUT, such that the
test harness can connect to the SUT with the test case generator.
• The initialization procedure initP must bring the SUT P into its initial state.
• The output procedure o = outP(i) has to compute the output of P based
on the current internal state of P and the input i. NotethatacalltooutP
is not allowed to change the state of P.
• Finally, the procedure nextP(i) hastobringP into the next state, again on
the basis of the current internal state and the input i.
The Lustre compiler which is provided for free by Verimag produces C-files
which are suitable for Lurette. Alternatively, the code generator of the SCADE
environment 4 can be used to obtain appropriate input files for Lurette. Other
synchronous languages are probably adaptable to Lurette by wrapping the generated
code into the above described procedures.
To integrate an oracle into a test harness, it must be provided in the same form
as the SUT P.
4 SCADE is a suite for developing dependable software, including tools to facilitate
specification, code generation, and code validation. It is based on a graphical implementation
of the Lustre language. See http://www.esterel-technologies.com.