Testing timed systems modeled by stream X-machines

Stream X-machines have been used to specify real systems where complex data structures. They are a variety of extended finite state machine where a shared memory is used to represent communications between the components of systems. In this paper we introduce an extension of the Stream X-machines formalism in order to specify systems that present temporal requirements. We add time in two different ways. First, we consider that (output) actions take time to be performed. Second, our formalism allows to specify timeouts. Timeouts represent the time a system can wait for the environment to react without changing its internal state. Since timeous affect the set of available actions of the system, a relation focusing on the functional behavior of systems, that is, the actions that they can perform, must explicitly take into account the possible timeouts. In this paper 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

Extending EFSMs to specify and test timed systems with action durations and timeouts

In this paper we introduce a timed extension of the extended finite state machines model. On the one hand, we consider that output actions take time to be performed. This time may depend on several factors such as the value of variables. On the other hand, our formalism allows to specify timeouts. In addition to present our formalism, we develop a testing theory. First, we define ten timed conformance relations and relate them. Second, we introduce a notion of timed test and define how to apply tests to IUTs

Test specification patterns for automatic generation of test sequences

Model Based Testing (MBT) enables automatic generation of test cases using models to specify the system behavior and requirements. Key features of MBT approaches are the automation level and the complexity of non-automated steps. Usually, test case generation is supported by some automatic technique whereas modeling is manually performed. UML statecharts or other extended finite state machine formalisms are widely used to build behavior models. To ease their development, as well as the extraction of test cases from them, is an important aspect to be addressed in order to perform testing activities with lower skill, cost and effort. This paper aims at providing a contribution to both the issues. Test Specification Patterns (TSPs) are proposed and expressed by means of UML annotated statecharts as a mean to aid the construction of models and build specifications on the base of well known recurring problems and their solutions (patterns). In order to improve usability and increase the automation level, a transformational approach is defined which derives Promela code from specifications built by TSPs composition and applies model checking to obtain test sequences by using the SPIN model checker. The usage of TSPs and the test case generation process is illustrated on a test scenario from the Radio Block Centre, the vital core of the modern railway control systems. © 2014 Springer International Publishing

Implementation relations and test generation for systems with distributed interfaces

This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2011 Springer-VerlagSome systems interact with their environment at physically distributed interfaces called ports and we separately observe sequences of inputs and outputs at each port. As a result we cannot reconstruct the global sequence that occurred and this reduces our ability to distinguish different systems in testing or in use. In this paper we explore notions of conformance for an input output transition system that has multiple ports, adapting the widely used ioco implementation relation to this situation. We consider two different scenarios. In the first scenario the agents at the different ports are entirely independent. Alternatively, it may be feasible for some external agent to receive information from more than one of the agents at the ports of the system, these local behaviours potentially being brought together and here we require a stronger implementation relation. We define implementation relations for these scenarios and prove that in the case of a single-port system the new implementation relations are equivalent to ioco. In addition, we define what it means for a test case to be controllable and give an algorithm that decides whether this condition holds. We give a test generation algorithm to produce sound and complete test suites. Finally, we study two implementation relations to deal with partially specified systems.This work was supported in part by Leverhulme Trust grant number F/00275/D, Natural Sciences and Engineering Research Council (NSERC) of Canada grant number OGP00000976, Testing State Based Systems, and Engineering and Physical Sciences Research Council grant number GR/R43150, Formal Methods and Testing (FORTEST)