Tester versus Bug: A Generic Framework for Model-Based Testing via Games

We propose a generic game-based approach for test case generation. We set up a game between the tester and the System Under Test, in such a way that test cases correspond to game strategies, and the conformance relation ioco corresponds to alternating refinement. We show that different test assumptions from the literature can be easily incorporated, by slightly varying the moves in the games and their outcomes. In this way, our framework allows a wide plethora of game-theoretic techniques to be deployed for model based testing.Comment: In Proceedings GandALF 2018, arXiv:1809.0241

State Identification for Labeled Transition Systems with Inputs and Outputs

For Finite State Machines (FSMs) a rich testing theory has been developed to discover aspects of their behavior and ensure their correct functioning. Although this theory is widely used, e.g., to check conformance of protocol implementations, its applicability is limited by restrictions of the FSM framework: the fact that inputs and outputs alternate in an FSM, and outputs are fully determined by the previous input and state. Labeled Transition Systems with inputs and outputs (LTSs), as studied in ioco testing theory, provide a richer framework for testing component oriented systems, but lack the algorithms for test generation from FSM theory. In this article, we propose an algorithm for the fundamental problem of state identification during testing of LTSs. Our algorithm is a direct generalization of the well-known algorithm for computing adaptive distinguishing sequences for FSMs proposed by Lee & Yannakakis. Our algorithm has to deal with so-called compatible states, states that cannot be distinguished in case of an adversarial system-under-test. Analogous to the result of Lee & Yannakakis, we prove that if an (adaptive) test exists that distinguishes all pairs of incompatible states of an LTS, our algorithm will find one. In practice, such adaptive tests typically do not exist. However, in experiments with an implementation of our algorithm on an industrial benchmark, we find that tests produced by our algorithm still distinguish more than 99% of the incompatible state pairs

With a little help from your friends: semi-cooperative games via Joker moves

This paper coins the notion of Joker games where Player 2 is not strictly adversarial: Player 1 gets help from Player 2 by playing a Joker. We formalize these games as cost games, and study their theoretical properties. Finally, we illustrate their use in model-based testing.Comment: Extended version with appendi

A predicate transformer for choreographies: Computing preconditions in choreographic programming

Construction and analysis of distributed systems is difficult; choreographic programming is a deadlock-freedom-by-construction approach to simplify it. In this paper, we present a new theory of choreographic programming. It supports for the first time: construction of distributed systems that require decentralised decision making (i.e., if/while-statements with multiparty conditions); analysis of distributed systems to provide not only deadlock freedom but also functional correctness (i.e., pre/postcondition reasoning). Both contributions are enabled by a single new technique, namely a predicate transformer for choreographies

JavaBIP meets VerCors: Towards the Safety of Concurrent Software Systems in Java

International audienceWe present "Verified JavaBIP", a tool set for the verification of JavaBIP models. A JavaBIP model is a Java program where classes are considered as components, their behaviour described by finite state machine and synchronization annotations. While JavaBIP guarantees execution progresses according to the indicated state machine, it does not guarantee properties of the data exchanged between components. It also does not provide verification support to check whether the behaviour of the resulting concurrent program is as (safe as) expected. This paper addresses this by extending the JavaBIP engine with run-time verification support, and by extending the program verifier VerCors to verify JavaBIP models deductively. These two techniques complement each other: feedback from run-time verification allows quicker prototyping of contracts, and deductive verification can reduce the overhead of run-time verification. We demonstrate our approach on the "Solidity Casino" case study, known from the VerifyThis Collaborative Long Term Challenge

Twelve week liraglutide or sitagliptin does not affect hepatic fat in type 2 diabetes: a randomised placebo-controlled trial

AIMS/HYPOTHESIS: Glucagon-like peptide (GLP)-1-based therapies have been suggested to improve hepatic steatosis. We assessed the effects of the GLP-1 receptor agonist liraglutide and the dipeptidyl peptidase (DPP)-4 inhibitor sitagliptin on hepatic steatosis and fibrosis in patients with type 2 diabetes. METHODS: In this 12 week, parallel, randomised, placebo-controlled trial, performed at the VU University Medical Center between July 2013 and August 2015, 52 overweight patients with type 2 diabetes treated with metformin and/or sulphonylurea agent ([mean ± SD] age 62.7 ± 6.9 years, HbA1c 7.3 ± 0.7% or 56 ± 1 mmol/mol) were allocated to once daily liraglutide 1.8 mg (n = 17), sitagliptin 100 mg (n = 18) or matching placebos (n = 17) by computer generated numbers. Both participants and researchers were blinded to group assignment. Hepatic fat content was measured using proton magnetic resonance spectroscopy ((1)H-MRS). Hepatic fibrosis was estimated using three validated formulae. RESULTS: One patient dropped out in the sitagliptin group owing to dizziness, but no serious adverse events occurred. At week 12, no between-group differences in hepatic steatosis were found. Liraglutide reduced steatosis by 10% (20.9 ± 3.4% to 18.8 ± 3.3%), sitagliptin reduced steatosis by 12.1% (23.9 ± 3.0% to 21.0 ± 2.7%) and placebo lessened it by 9.5% (18.7 ± 2.7% to 16.9 ± 2.7%). Neither drug affected hepatic fibrosis scores compared with placebo. CONCLUSIONS/INTERPRETATION: Twelve-week liraglutide or sitagliptin treatment does not reduce hepatic steatosis or fibrosis in type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov NCT01744236 FUNDING : Funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 282521 - the SAFEGUARD project

Twelve week liraglutide or sitagliptin does not affect hepatic fat in type 2 diabetes: a randomised placebo-controlled trial

_Aims/hypothesis:_ Glucagon-like peptide (GLP)-1-based therapies have been suggested to improve hepatic steatosis. We assessed the effects of the GLP-1 receptor agonist liraglutide and the dipeptidyl peptidase (DPP)-4 inhibitor sitagliptin on hepatic steatosis and fibrosis in patients with type 2 diabetes. _Methods:_ In this 12 week, parallel, randomised, placebo-controlled trial, performed at the VU University Medical Center between July 2013 and August 2015, 52 overweight patients with type 2 diabetes treated with metformin and/or sulphonylurea agent ([mean ± SD] age 62.7 ± 6.9 years, HbA1c 7.3 ± 0.7% or 56 ± 1 mmol/mol) were allocated to once daily liraglutide 1.8 mg (n = 17), sitagliptin 100 mg (n = 18) or matching placebos (n = 1