Automated unique input output sequence generation for conformance testing of FSMs

This paper describes a method for automatically generating unique input output (UIO) sequences for FSM conformance testing. UIOs are used in conformance testing to verify the end state of a transition sequence. UIO sequence generation is represented as a search problem and genetic algorithms are used to search this space. Empirical evidence indicates that the proposed method yields considerably better (up to 62% better) results compared with random UIO sequence generation

Chaining Test Cases for Reactive System Testing (extended version)

Testing of synchronous reactive systems is challenging because long input sequences are often needed to drive them into a state at which a desired feature can be tested. This is particularly problematic in on-target testing, where a system is tested in its real-life application environment and the time required for resetting is high. This paper presents an approach to discovering a test case chain---a single software execution that covers a group of test goals and minimises overall test execution time. Our technique targets the scenario in which test goals for the requirements are given as safety properties. We give conditions for the existence and minimality of a single test case chain and minimise the number of test chains if a single test chain is infeasible. We report experimental results with a prototype tool for C code generated from Simulink models and compare it to state-of-the-art test suite generators.Comment: extended version of paper published at ICTSS'1

Distinguishing sequences for partially specified FSMs

Distinguishing Sequences (DSs) are used inmany Finite State Machine (FSM) based test techniques. Although Partially Specified FSMs (PSFSMs) generalise FSMs, the computational complexity of constructing Adaptive and Preset DSs (ADSs/PDSs) for PSFSMs has not been addressed. This paper shows that it is possible to check the existence of an ADS in polynomial time but the corresponding problem for PDSs is PSPACE-complete. We also report on the results of experiments with benchmarks and over 8 * 106 PSFSMs. © 2014 Springer International Publishing

Improved test quality using robust unique input/output circuit sequences (UIOCs)

In finite state machine (FSM) based testing, the problem of fault masking in the unique input/ output (UIO) sequence may degrade the test performance of the UIO based methods. This paper investigates this problem and proposes the use of a new type of unique input/output circuit (UIOC) sequence for state verification, which may help to overcome the drawbacks that exist in the UIO based techniques. When constructing a UIOC, overlap and internal state observation schema are used to increase the robustness of a test sequence. Test quality is compared by using the forward UIO method (F-method), the backward UIO method (B-method) and the UIOC method (C-method) separately. Robustness of the UIOCs constructed by the algorithm given in this paper is also compared with those constructed by the algorithm given previously. Experimental results suggest that the C-method outperforms the F- and the B-methods and the UIOCs constructed by the Algorithm given in this paper, are more robust than those constructed by other proposed algorithms

Using formal methods to support testing

Formal methods and testing are two important approaches that assist in the development of high quality software. While traditionally these approaches have been seen as rivals, in recent years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing

Estimating the feasibility of transition paths in extended finite state machines

There has been significant interest in automating testing on the basis of an extended finite state machine (EFSM) model of the required behaviour of the implementation under test (IUT). Many test criteria require that certain parts of the EFSM are executed. For example, we may want to execute every transition of the EFSM. In order to find a test suite (set of input sequences) that achieves this we might first derive a set of paths through the EFSM that satisfy the criterion using, for example, algorithms from graph theory. We then attempt to produce input sequences that trigger these paths. Unfortunately, however, the EFSM might have infeasible paths and the problem of determining whether a path is feasible is generally undecidable. This paper describes an approach in which a fitness function is used to estimate how easy it is to find an input sequence to trigger a given path through an EFSM. Such a fitness function could be used in a search-based approach in which we search for a path with good fitness that achieves a test objective, such as executing a particular transition, and then search for an input sequence that triggers the path. If this second search fails then we search for another path with good fitness and repeat the process. We give a computationally inexpensive approach (fitness function) that estimates the feasibility of a path. In order to evaluate this fitness function we compared the fitness of a path with the ease with which an input sequence can be produced using search to trigger the path and we used random sampling in order to estimate this. The empirical evidence suggests that a reasonably good correlation (0.72 and 0.62) exists between the fitness of a path, produced using the proposed fitness function, and an estimate of the ease with which we can randomly generate an input sequence to trigger the path

Constructing multiple unique input/output sequences using metaheuristic optimisation techniques

Multiple unique input/output sequences (UIOs) are often used to generate robust and compact test sequences in finite state machine (FSM) based testing. However, computing UIOs is NP-hard. Metaheuristic optimisation techniques (MOTs) such as genetic algorithms (GAs) and simulated annealing (SA) are effective in providing good solutions for some NP-hard problems. In the paper, the authors investigate the construction of UIOs by using MOTs. They define a fitness function to guide the search for potential UIOs and use sharing techniques to encourage MOTs to locate UIOs that are calculated as local optima in a search domain. They also compare the performance of GA and SA for UIO construction. Experimental results suggest that, after using a sharing technique, both GA and SA can find a majority of UIOs from the models under test

Testing a distributed system: Generating minimal synchronised test sequences that detect output-shifting faults

A distributed system may have a number of separate interfaces called ports and in testing it may be necessary to have a separate tester at each port. This introduces a number of issues, including the necessity to use synchronised test sequences and the possibility that output-shifting faults go undetected. This paper considers the problem of generating a minimal synchronised test sequence that detects output-shifting faults when the system is specified using a finite state machine with multiple ports. The set of synchronised test sequences that detect output-shifting faults is represented by a directed graph G and test generation involves finding appropriate tours of G. This approach is illustrated using the test criterion that the test sequence contains a test segment for each transition

Generating synchronizable test sequences with overlaps

Finite-state-machine-based conformance testing has been comprehensively studied in the literature in the context of centralized test architecture. As distributed test architecture involves multiple remote testers, applying a test sequence generated from a given n-port finite state machine to an implementation under test (IUT) may result in controllability problems. A possible way to resolve this problem is to select an appropriate test sequence, whose application to the IUT will not involve controllability problems. Thus generating such efficient test sequences is an interesting issue. There are several possibilities for such test sequence generation and we provide empirical study to compare the efficiency of two typical solutions proposed in the literature in terms of the length of the generated test sequences. While both of the two techniques rely on solutions to the Rural Postman Problem (RPP), a well-used RPP solution has been adopted and further improved in this thesis work