arXiv subjects

Laura Brandán Briones

Publications and source records attributed to Laura Brandán Briones.

3 recordsLinked to original sources

arXiv2026

Quiescence in Concert: Composing Multi-Channel Time-Outs for IOCO

In Model-Based Testing (MBT), test suites are generated automatically from a formal specification. The theory of testing real-time systems is rich, but often underused in practice, partly because applying the timed machinery demands expertise practitioners should not need. In prior work we addressed this for timed testing with a canonic lifting operator, which lets a modeller specify behaviour as plain labelled transition systems while implicitly obtaining the timed automata that express their quiescent behaviour (the explicit absence of outputs) with timers. This paper takes the next step: we show that our lifting still works when each component carries its own time-out on its own channel. This way, we introduce a multi-channel lifting. We show that it commutes with parallel composition, i.e. composing and lifting is the same as lifting first and then composing. We show that the MBT apparatus survives: conformance, test generation and verdicts are preserved by the lifting, on the testable traces that a time-out based tester can observe.

cs.SE↗

arXiv2025

Time for Quiescence: Modelling quiescent behaviour in testing via time-outs in timed automata

Model-based testing (MBT) derives test suites from a behavioural specification of the system under test. In practice, engineers favour simple models, such as labelled transition systems (LTSs). However, to deal with quiescence - the absence of observable output - in practice, a time-out needs to be set to conclude observation of quiescence. Timed MBT exists, but it typically relies on the full arsenal of timed automata (TA). We present a lifting operator $χ^{\scriptstyle M}\!$ that adds timing without the TA overhead: given an LTS, $χ^{\scriptstyle M}\!$ introduces a single clock for a user chosen time bound $M>0$ to declare quiescence. In the timed automaton, the clock is used to model that outputs should happen before the clock reaches value $M$, while quiescence occurs exactly at time $M$. This way we provide a formal basis for the industrial practice of choosing a time-out to conclude quiescence. Our contributions are threefold: (1) an implementation conforms under $\mathbf{ioco}$ if and only if its lifted version conforms under timed $\mathbf{tioco_M}$ (2) applying $χ^{\scriptstyle M}\!$ before or after the standard $\mathbf{ioco}$ test-generation algorithm yields the same set of tests, and (3) the lifted TA test suite and the original LTS test suite deliver identical verdicts for every implementation.

cs.FL↗

arXiv2015

Distributed Analysis for Diagnosability in Concurrent Systems

Complex systems often exhibit unexpected faults that are difficult to handle. Such systems are desirable to be diagnosable, i.e. faults can be automatically detected as they occur (or shortly afterwards), enabling the system to handle the fault or recover. A system is diagnosable if it is possible to detect every fault, in a finite time after they occurred, by only observing the available information from the system. Complex systems are usually built from simpler components running concurrently. We study how to infer the diagnosability property of a complex system (distributed and with multiple faults) from a parallelized analysis of the diagnosability of each of its components synchronizing with fault free versions of the others. In this paper we make the following contributions: (1) we address the diagnosability problem of concurrent systems with arbitrary faults occurring freely in each component. (2) We distribute the diagnosability analysis and illustrate our approach with examples. Moreover, (3) we present a prototype tool that implements our techniques showing promising results.

cs.SE↗