Model Based Security Testing for Autonomous Vehicles

The purpose of this dissertation is to introduce a novel approach to generate a security test suite to mitigate malicious attacks on an autonomous system. Our method uses model based testing (MBT) methods to model system behavior, attacks and mitigations as independent threads in an execution stream. The threads intersect at a rendezvous or attack point. We build a security test suite from a behavioral model, an attack type and a mitigation model using communicating extended finite state machine (CEFSM) models. We also define an applicability matrix to determine which attacks are possible with which states. Our method then builds a comprehensive test suite using edge-node coverage that allows for systematic testing of an autonomous vehicle

Fail-Safe Testing of Safety-Critical Systems

This dissertation proposes an approach for testing of safety-critical systems. It is based on a behavioral and a fault model. The two models are analyzed for compatibility and necessary changes are identified to make them compatible. Then transformation rules are used to transform the fault model into the same model type as the behavioral model. Integration rules define how to combine them. This approach results in an integrated model which then can be used to generate tests using a variety of testing criteria. The dissertation illustrates this general framework using a CEFSM for the behavioral model and a Fault Tree for the fault model. We apply the technique to a variety of applications such as a Gas burner, an Aerospace Launch System, and a Railroad Crossing Control System. We also investigate the scalability of the approach and compare its efficiency with integrating a state chart and a fault tree. Construction and Analysis of Distributed Processes (CADP) has been used as a supporting tool for this approach to generate test cases from the integrated model and to analyze the integrated model for some properties such as deadlock and livelock

Fail-Safe Test Generation of Safety Critical Systems

This dissertation introduces a technique for testing proper failure mitigation in safety critical systems. Unlike other approaches which integrate behavioral and failure models, and then generate tests from the integrated model, we build safety mitigation tests from an existing behavioral test suite, using an explicit mitigation model for which we generate mitigation paths which are then woven at selected failure points into the original test suite to create failure-mitigation tests (safety mitigation test)

Model-Based Testing of Smart Home Systems Using EFSM, CEFSM, and FSMApp

Smart Home Systems (SHS) are some of the most popular Internet of Things (IoT) applications. In 2021, there were 52.22 million smart homes in the United States and they are expected to grow to 77.1 million in 2025 [71]. According to MediaPost [74], 69 percent of American households have at least one smart home device. The number of smart home systems poses a challenge for software testers to find the right approach to test these systems. This dissertation employs Extended Finite State Machines (EFSMs) [6, 24, 105], Communicating Extended Finite State Machines (EFSMs) [68] and FSMApp [10] to generate reusable test-ready models of smart home systems. We present an approach to create reusable test-ready models of smart home systems using EFSMs to model device components (Sensor, Controller and Actuator), EFSMs to model single devices in the SHS and the interaction between the devices. We adopted Al Haddad’s [10] FSMApp approach to model and test the mobile application that controls the SHS. These reusable test-ready models were used to generate tests. This dissertation also addresses evolution in smart home systems. Evolution is classified into three categories: adding a new device, updating an excising device or removing one. A method for selective black-box model-based regression testing for these changes was proposed

A Review of Software Reliability Testing Techniques

In the era of intelligent systems, the safety and reliability of software have received more attention. Software reliability testing is a significant method to ensure reliability, safety and quality of software. The intelligent software technology has not only offered new opportunities but also posed challenges to software reliability technology. The focus of this paper is to explore the software reliability testing technology under the impact of intelligent software technology. In this study, the basic theories of traditional software and intelligent software reliability testing were investigated via related previous works, and a general software reliability testing framework was established. Then, the technologies of software reliability testing were analyzed, including reliability modeling, test case generation, reliability evaluation, testing criteria and testing methods. Finally, the challenges and opportunities of software reliability testing technology were discussed at the end of this paper

Medical Device Interoperability With Provable Safety Properties

Applications that can communicate with and control multiple medical devices have the potential to radically improve patient safety and the effectiveness of medical treatment. Medical device interoperability requires devices to have an open, standards-based interface that allows communication with any other device that implements the same interface. This will enable applications and functionality that can improve patient safety and outcomes. To build interoperable systems, we need to match up the capabilities of the medical devices with the needs of the application. An application that requires heart rate as an input and provides a control signal to an infusion pump requires a source of heart rate and a pump that will accept the control signal. We present means for devices to describe their capabilities and a methodology for automatically checking an application’s device requirements against the device capabilities. If such applications are going to be used for patient care, there needs to be convincing proof of their safety. The safety of a medical device is closely tied to its intended use and use environment. Medical device manufacturers create a hazard analysis of their device, where they explore the hazards associated with its intended use. We describe hazard analysis for interoperable devices and how to create system safety properties from these hazard analyses. The use environment of the application includes the application, connected devices, patient, and clinical workflow. The patient model is specific to each application and represents the patient’s response to treatment. We introduce Clinical Application Modeling Language (CAML), based on Extended Finite State Machines, and use model checking to test safety properties from the hazard analysis against the parallel composition of the application, patient model, clinical workflow, and the device models of connected devices

Improving fault coverage and minimising the cost of fault identification when testing from finite state machines

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Software needs to be adequately tested in order to increase the confidence that the system being developed is reliable. However, testing is a complicated and expensive process. Formal specification based models such as finite state machines have been widely used in system modelling and testing. In this PhD thesis, we primarily investigate fault detection and identification when testing from finite state machines. The research in this thesis is mainly comprised of three topics - construction of multiple Unique Input/Output (UIO) sequences using Metaheuristic Optimisation Techniques (MOTs), the improved fault coverage by using robust Unique Input/Output Circuit (UIOC) sequences, and fault diagnosis when testing from finite state machines. In the studies of the construction of UIOs, a model is proposed where a fitness function is defined to guide the search for input sequences that are potentially UIOs. In the studies of the improved fault coverage, a new type of UIOCs is defined. Based upon the Rural Chinese Postman Algorithm (RCPA), a new approach is proposed for the construction of more robust test sequences. In the studies of fault diagnosis, heuristics are defined that attempt to lead to failures being observed in some shorter test sequences, which helps to reduce the cost of fault isolation and identification. The proposed approaches and techniques were evaluated with regard to a set of case studies, which provides experimental evidence for their efficacy.Brunel Research Initiative and Enterprise Fund (BRIEF) Award from Brunel University and Departmental bursary from Department of Information Systems and Computing, Brunel Universit