Input Output Symbolic Transition Systems Enriched by Program Calls and Contracts: a detailed example of vending machine

An Input Output Symbolic Transition System (IOSTS) specifies all expected sequences of input and output messages of a reactive system. Symbolic execution over this IOSTS then allows to generate a set of test cases that can exercise the various possible behaviors of the system it represents. In this paper, we extend the IOSTS framework with explicit program calls, possibly equipped with contracts specifying what the program is supposed to do. This approach bridges the gap between a model-based approach in which user-defined programs are abstracted away and a code-based approach in which small pieces of code are separately considered regardless of the way they are combined. First, we extend symbolic execution techniques for IOSTS with programs, in order to re-use classical test case generation algorithms. Second, we explore how constraints coming from IOSTS symbolic execution can be used to infer contracts for programs used in the IOSTS

Test à base de modèles : IOSTS enrichis avec les appels de fonctions

Les systèmes réactifs sont modélisés avec différents types d'automates, tels que les systèmes de transitions symboliques à entrée sortie (IOSTS). L'exécution symbolique d'un IOSTS permet la génération de cas de test qui peuvent être exécutés sur une implantation concrète, afin de déterminer si elle est conforme à son modèle. Dans ce document, nous étendons les IOSTS avec des appels de fonctions utilisateur et analysons leur impact sur le système entier et viceversa. Cette thèse comble l'écart entre une approche basée sur le modèle où les fonctions utilisateur sont abstraites et une approche basée sur le code où les petits morceaux de code sont considérés séparément, indépendamment de la façon dont ils sont combinés. Selon le niveau de connaissance que nous avons sur ces fonctions, elles sont modélisées soit par une spécification complète, soit par une spécification partielle, soit juste comme des boîtes noires fournies sans aucune connaissance. Premièrement, lorsque les fonctions sont partiellement connues, nous utilisons des bouchons définis par des tables contenant des tuples représentatifs des données d'entrée/sortie. L'approche proposée emprunte au test "concolic", l'idée de mélanger l'exécution symbolique avec l'information obtenue à partir d'exécutions concrètes des fonctions (tables). Deuxièmement, si l'utilisateur est prêt à fournir d'autres spécifications, il serait intéressant d'utiliser des représentations plus complètes pour les fonctions. Par conséquent, nous proposons d'abstraire des comportements des fonctions par des contrats pré/post. Ensuite, nous étendons l'exécution symbolique en analysant les fonctions via leurs contrats. Enfin, lorsque les fonctions appelées sont complètement inconnues, nous présentons une approche pour extraire de nouveaux contrats pour eux en explorant les contraintes issues de l'exécution symbolique de l'IOSTS. De tels contrats reflètent les contraintes des fonctions qui rendent possible un certain comportement (exigence).Reactive systems are modeled with various kinds of automata, such as Input Output Symbolic Transition Systems (IOSTS). Symbolic execution over an IOSTS allows test cases generation that can be executed on a concrete implementation, in order to determine whether it is conforming to its model. In this dissertation, we aim at extending the IOSTS framework with explicit user-defined function calls and analyze their impact on a whole system and vice-versa. The thesis bridges the gap between a model-based approach in which user-defined functions are abstracted away and a code-based approach in which small pieces of code are considered separately regardless of the way they are combined. According to the level of knowledge we have about these functions, they are modeled either by a complete specification, a partial specification, or even just as black-boxes provided without any knowledge. First, when functions are partially known, we use function stubs defined by tables containing representative input/output data tuples. The proposed approach borrows from concolic testing, the idea of mixing symbolic execution with information obtained from instrumented concrete executions (function tables). Second, if the user is willing to provide further specifications, it would be interesting to use more complete representations for called functions. Hence, we propose to abstract function behaviors by means of pre/post contracts. Then we extend symbolic execution by analyzing the functions through their contracts. Finally, when called functions are completely unknown, we present an approach to extract new contracts for them by exploring constraints coming from the IOSTS symbolic execution. Such contracts reflect constraints on the functions that make some behavior (requirement) feasible

Model-based Testing from Input Output Symbolic Transition Systems Enriched by Program Calls and Contracts

International audienceAn Input Output Symbolic Transition System (IOSTS) specifies all expected sequences of input and output messages of a reactive system. Symbolic execution over this IOSTS then allows to generate a set of test cases that can exercise the various possible behaviors of the system it represents. In this paper, we extend the IOSTS framework with explicit program calls, possibly equipped with contracts specifying what the program is supposed to do. This approach bridges the gap between a model-based approach in which user-defined programs are abstracted away and a code-based approach in which small pieces of code are separately considered regardless of the way they are combined. First, we extend symbolic execution techniques for IOSTS with programs, in order to re-use classical test case generation algorithms. Second, we explore how constraints coming from IOSTS symbolic execution can be used to infer contracts for programs used in the IOSTS

Validation of the Mental Toughness Measure of Athletes and Non-athletes with the Structural Equation Model

The use of structural equation models (SEM) in scientific research perform a promising methodological and empirical direction to validate the measurement of psychological constructs. The aim of this paper is to validate the measurement of mental toughness of athletes and non-athletes with SEM. The sample consisted of 853 Tunisian participants (444 males and 409 females; 409 athletes and 444 non-athletes), aged 14 to 27 years (M=20.38 SD=4.12). The sample completed the Arabic translated questionnaire of Clough, Earle [1] which measures six components of their mental toughness. The SEM approved a good model fit (χ²=1146.33; df =1065; CFI=.93; SRMR=.063; RMSEA=.009) which allows for a valid Arabic-speaking measure of the six components of mental toughness

Symbolic execution of transition systems with function summaries

International audienceReactive systems can be modeled with various kinds of au-tomata, such as Input Output Symbolic Transition Systems (IOSTS). Symbolic execution (SE) applied to IOSTS allows computing constraints associated to IOSTS path executions (path conditions). In this context, generating test cases amounts to finding numerical input values satisfying such constraints using solvers. This paper explores the case where IOSTS models contain functions which are outside of the scope of such solvers. We propose to use function summaries which are logical formulas built from concrete values describing some representative input/output data tuples of the function. We define algorithmic strategies to solve path conditions including such functions based on techniques using and enriching function summaries. Our method has been implemented within the Diversity tool and has been applied to several examples