Towards Symbolic Model-Based Mutation Testing: Combining Reachability and Refinement Checking

Model-based mutation testing uses altered test models to derive test cases that are able to reveal whether a modelled fault has been implemented. This requires conformance checking between the original and the mutated model. This paper presents an approach for symbolic conformance checking of action systems, which are well-suited to specify reactive systems. We also consider nondeterminism in our models. Hence, we do not check for equivalence, but for refinement. We encode the transition relation as well as the conformance relation as a constraint satisfaction problem and use a constraint solver in our reachability and refinement checking algorithms. Explicit conformance checking techniques often face state space explosion. First experimental evaluations show that our approach has potential to outperform explicit conformance checkers.Comment: In Proceedings MBT 2012, arXiv:1202.582

De la composition de systèmes temporisés

The composition of timed systems is a source of problems, in particular of deadlocks. Our goal in this work is to provide a framework for the compositional description of timed systems which preserves time reactivity, that is the property that time can progress if a system cannot react. To achieve this, we first study the specification of timed evolutions, leading to the definition of adequate description mechanisms. This allows the definition of a class of timed models which are structurally time reactive. We define on this class choice operators and parallel composition operators preserving this property. Moreover, these operators are defined in such a way that activity is preserved, which means that if from a state a component can make an action then the composed system can make an action too. The parallel composition operator satisfies also the property of maximal progress by using priority choice operators which give preference to synchronizations. A general framework is given to define synchronization modes, such as AND (usual synchronization), MAX (synchronization with waiting) and MIN (interruption). Finally, we develop an algebraic approach for a subclass of the considered models.La composition des systèmes temporisés est source de nombreux problèmes, notamment de blocage. Nous proposons un cadre de description compositionnelle des systèmes temporisés qui préserve la réactivité temprorelle, à savoir que si le système ne peut réagir, alors le temps peut avancer. Nous effectuons d'abord une étude préliminaire sur la spécification des évolutions temporelles dans les systèmes, débouchant sur la définition de mécanismes de description adéquats. Ceci nous permet de définir une classe de modèles temporisés temporellement réactifs, par construction. Nous définissons sur cette classe des opérateurs de choix et de composition parallèle qui préservent cette propriété. En outre, les opérateurs sont définis de sorte à préserver l'activité dans le sens où si à partir d'un état une action est possible dans un composant, alors une action est possible dans la composition. L'opérateur de composition parallèle respecte également la propriété de progrès maximal grâce à l'utilisation d'opérateurs de choix avec priorités qui favorise les synchronisations. Un cadre général est donné pour exprimer différents modes de synchronisation, parmi lesquels on retiendra AND (synchronisation classique), MAX (synchronisation avec attente) et MIN (interruption). Pour terminer, nous développons une approche algébrique pour une sous-classe des modèles considérés

Relating Time Progress and Deadlines in Hybrid Systems

Time progress conditions in hybrid systems are usually specified in terms of invariants, predicates characterizing states where time can continuously progress or dually, deadline conditions, predicates characterizing states where time progress immediately stops. The aim of this work is the study of relationships between general time progress conditions and these generated by using state predicates. It is shown that using deadline conditions or invariantsf allows to characterize all practically interesting time progress conditions. The study is performed by using a Galois connection between the corresponding lattices. We provide conditions for the connection to be a homomorphism and apply the results to the compositional description of hybrid systems

On the Composition of Hybrid Systems

Introduction Concurrent systems can be usually specified as systems of communicating processes obtained by composing sequential processes by means of binary parallel composition operators. The latter express process interaction in terms of action composition. Their semantics is usually defined by two types of rules. -- Synchronization rules that specify how an action of the product process is defined as the result of the (simultaneous) occurrence of two actions in two component processes. -- Interleaving rules, that specify how an action of a component process is an action of the product process. These rules allow some component processes to be idle while the others progress. Combining synchronization and interleaving rules is essential for the specification of systems as process coordination requires both synchronization and waiting. However, their adequate combination must satisfy two conflicting requirements : Deadlock-freedom<F52