Testing from a stochastic timed system with a fault model

In this paper we present a method for testing a system against a non-deterministic stochastic finite state machine. As usual, we assume that the functional behaviour of the system under test (SUT) is deterministic but we allow the timing to be non-deterministic. We extend the state counting method of deriving tests, adapting it to the presence of temporal requirements represented by means of random variables. The notion of conformance is introduced using an implementation relation considering temporal aspects and the limitations imposed by a black-box framework. We propose an algorithm for generating a test suite that determines the conformance of a deterministic SUT with respect to a non-deterministic specification. We show how previous work on testing from stochastic systems can be encoded into the framework presented in this paper as an instantiation of our parameterized implementation relation. In this setting, we use a notion of conformance up to a given confidence level

Constraint-Based Heuristic On-line Test Generation from Non-deterministic I/O EFSMs

We are investigating on-line model-based test generation from non-deterministic output-observable Input/Output Extended Finite State Machine (I/O EFSM) models of Systems Under Test (SUTs). We propose a novel constraint-based heuristic approach (Heuristic Reactive Planning Tester (xRPT)) for on-line conformance testing non-deterministic SUTs. An indicative feature of xRPT is the capability of making reasonable decisions for achieving the test goals in the on-line testing process by using the results of off-line bounded static reachability analysis based on the SUT model and test goal specification. We present xRPT in detail and make performance comparison with other existing search strategies and approaches on examples with varying complexity.Comment: In Proceedings MBT 2012, arXiv:1202.582

Testing conformance to a quasi-non-deterministic stream X-machine

Stream X-machines have been used in order to specify a range of systems. One of the strengths of this approach is that, under certain well-defined conditions, it is possible to produce a finite test that is guaranteed to determine the correctness of the implementation under test (IUT). Initially only deterministic stream X-machines were considered in the literature. This is largely because the standard test algorithm relies on the stream X-machine being deterministic. More recently the problem of testing to determine whether the IUT is equivalent to a non-deterministic stream X-machine specification has been tackled. Since non-determinism can be important for specifications, this is an extremely useful extension. In many cases, however, we wish to test for a weaker notion of correctness called conformance. This paper considers a particular form of non-determinism, within stream X-machines, that will be called quasi-non-determinism. It then investigates the generation of tests that are guaranteed to determine whether the IUT conforms to a quasi-non-deterministic stream X-machine specification. The test generation algorithm given is a generalisation of that used for testing from a deterministic stream X-machine

Test of preemptive real-time systems

Time Petri nets with stopwatches not only model system/environment interactions and time constraints. They further enable modeling of suspend/resume operations in real-time systems. Assuming the modelled systems are non deterministic and partially observable, the paper proposes a test generation approach which implements an online testing policy and outputs test results that are valid for the (part of the) selected environment. A relativized conformance relation named rswtioco is defined and a test generation algorithm is presented. The proposed approach is illustrated on an example

Online Testing of Real-Time Systems Using UPPAAL: Status and Future Work

We present TUPPAAL --- a new tool for online black-box testing of real-time embedded systems from non-deterministic timed automata specifications. We describe a sound and complete randomized online testing algorithm, and describe how to implement it using symbolic state representation and manipulation techniques. We propose the notion of relativized timed input/output conformance as the formal implementation relation. A novelty of this relation and our testing algorithm is that they explicitly take environment assumptions into account, generate, execute and verify the result online using the UPPAAL on-the-fly model-checking tool engine. A medium size case study shows promising results in terms of error detection capability and computation performance

Towards Symbolic Model-Based Mutation Testing: Combining Reachability and Refinement Checking

Model-based mutation testing uses altered test models to derive test cases that are able to reveal whether a modelled fault has been implemented. This requires conformance checking between the original and the mutated model. This paper presents an approach for symbolic conformance checking of action systems, which are well-suited to specify reactive systems. We also consider nondeterminism in our models. Hence, we do not check for equivalence, but for refinement. We encode the transition relation as well as the conformance relation as a constraint satisfaction problem and use a constraint solver in our reachability and refinement checking algorithms. Explicit conformance checking techniques often face state space explosion. First experimental evaluations show that our approach has potential to outperform explicit conformance checkers.Comment: In Proceedings MBT 2012, arXiv:1202.582

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

Testing conformance of a deterministic implementation against a non-deterministic stream X-machine

Stream X-machines are a formalisation of extended finite state machines that have been used to specify systems. One of the great benefits of using stream X-machines, for the purpose of specification, is the associated test generation technique which produces a test that is guaranteed to determine correctness under certain design for test conditions. This test generation algorithm has recently been extended to the case where the specification is non-deterministic. However, the algorithms for testing from a non-deterministic stream X-machine currently have limitations: either they test for equivalence, rather than conformance or they restrict the source of non-determinism allowed in the specification. This paper introduces a new test generation algorithm that overcomes both of these limitations, for situations where the implementation is known to be deterministic