Extending stream X-machines to specify and test systems with timeouts

Stream X-machines are a kind of extended finite state machine used to specify real systems where communication between the components is modeled by using a shared memory.In this paper we introduce an extension of the Stream X-machines formalism in order to specify delays/timeouts.The time spent by a system waiting for the environment to react has the capability of affecting the set of available outputs of the system. So, a relation focusing on functional aspects must explicitly take into account the possible timeouts.We also propose a formal testing methodology allowing to systematically test a system with respect to a specification. Finally, we introduce a test derivation algorithm. Given a specification, the derived test suite is sound and complete, that is, a system under test successfully passes the test suite if and only if this system conforms to the specification

Testing microcontroller based physical systems using finite transition models

Many devices of controlling parts of physica

Formal Testing of Timed and Probabilistic Systems

Abstract. This talk reviews some of my contributions on formal testing of timed and probabilistic systems, focusing on methodologies that allow their users to decide whether these systems are correct with respect to a formal specification. The consideration of time and probability complicates the definition of these frameworks since there is not an obvious way to define correctness. For example, in a specific situation it might be desirable that a system is as fast as possible while in a different application it might be required that the performance of the system is exactly equal to the one given by the specification. All the methodologies have as common assumption that the system under test is a black-box and that the specification is described as a timed and/or probabilistic extension of the finite state machines formalism

Formal testing of systems presenting soft and hard deadlines

We present a formal framework to specify and test systems presenting both soft and hard deadlines. While hard deadlines must be always met on time, soft deadlines can be sometimes met in a different time, usually higher, from the specified one. It is this characteristic (to formally define sometimes) what produces several reasonable alternatives to define appropriate implementation relations, that is, relations to decide wether an implementation is correct with respect to a specification. In addition to introduce these relations, we define a testing framework to test implementations

Distinguishing experiments for timed nondeterministic finite state machine

The problem of constructing distinguishing experiments is a fundamental problem in the area of finite state machines (FSMs), especially for FSM-based testing. In this paper, the problem is studied for timed nondeterministic FSMs (TFSMs) with output delays. Given two TFSMs, we derive the TFSM intersection of these machines and show that the machines can be distinguished using an appropriate (untimed) FSM abstraction of the TFSM intersection. The FSM abstraction is derived by constructing appropriate partitions for the input and output time domains of the TFSM intersection. Using the obtained abstraction, a traditional FSM-based preset algorithm can be used for deriving a separating sequence for the given TFSMs if these machines are separable. Moreover, as sometimes two non-separable TFSMs can still be distinguished by an adaptive experiment, based on the FSM abstraction we present an algorithm for deriving an r-distinguishing TFSM that represents a corresponding adaptive experiment

Formal correctness of a passive testing approach for timed systems

In this paper we extend our previous work on passive testing of timed systems to establish a formal criterion to determine correctness of an implementation under test. In our framework, an invariant expresses the fact that if the implementation under test performs a given sequence of actions, then it must exhibit a behavior in a lapse of time reflected in the invariant. In a previous paper we gave an algorithm to establish the correctness of an invariant with respect to a specification. In this paper we continue the work by providing an algorithm to check the correctness of a log, recorded form the implementation under test, with respect to an invariant. We show the soundness of our method by relating it to an implementation relation. In addition to the theoretical framework we have developed a tool, called PASTE, that facilitates the automation of our passive testing approach

Advantages of mutation in passive testing: An empirical study

This paper presents an empirical study of the mutation techniques used by the tool PASTE. This tool allows the automation of our passive testing methodology for systems that present stochastic-time information. In our proposal, invariants express the fact that each time the implementation under test performs a given sequence of actions, then it must exhibit a behavior according to the probability distribution functions reflected in the invariant. We briefly review the theoretical framework of our methodology and the main features of our tool. Next, we present in detail the Mutants module that provides us with a functionality to test the effectiveness of invariants for detecting errors. Finally, we present a study of the results obtained from the performed experiments

Analysis of the OLSR Protocol by Using Formal Passive Testing

In this paper we apply a passive testing methodology to the analysis of a non-trivial system. In our framework, so-called invariants provide us with a formal representation of the requirements of the system. In order to precisely express new properties in multi-node environments, in this paper we introduce a new kind of invariants. We apply the resulting framework to perform a complete study of a MANET routing protocol: The Optimized Link State Routing protocol

Passive Testing of Stochastic Timed Systems

In this paper we introduce a formal Methodology to perforin passive testing, based on invariants, for systems where the passing of time is represented in probabilistic terms by means of probability distributions functions. In our approach, invariants express the fact that each time the implementation under test performs a given sequence of actions, then it must exhibit a behavior according to the probability distribution functions reflected it? the invariant. We present algorithms to decide the correctness of the proposed invariants with respect to a given specification. Once we know that an invariant is correct, we check whether the execution traces observed from the implementation respect the invariant. In addition to the theoretical framework we have developed a tool., called PASTE, that helps in the automation of our passive testing approach. We have used the tool to obtain experimental results front the application of our methodology

Applying formal passive testing to study temporal properties of the Stream Control Transmission Protocol

In this paper we present a formal passive testing framework and use it to analyze time aspects in the Stream Control Transmission Protocol (SCTP). This protocol presents different phases where time aspects are critical. In order to represent temporal requirements we use so-called timed invariants since they allow us to easily verify that the traces collected from the observation of the protocol fulfill the corresponding timed constraints. In addition to introduce our theoretical framework, we report on the results obtained from the application of our techniques over (possibly mutated) traces extracted from runs of the SCTP