Research

I develop techniques and tools to improve the trustworthiness and reliability of software and cyber-physical systems. I am particularly interested in finding ways to test “hard to test” systems, with long execution times, non-determinism, limited state observability, and large input / output spaces.

My research has been funded by the EPSRC (CITCOM, REGI, and STAMINA projects), InnovateUK, DSTL, and the DfT.

I am currently joint PC-chair for the International Conference on Software Testing (ICST’26). I am an associate editor for the Journal of Automated Software Engineering.

My research publications can be found on Google Scholar. Some key publications are highlighted below.

Causal Software Engineering

Much of my recent research has focused on the application of Causal Inference to test causal input - output relationships in software and cyberphysical systems. Our work has focussed on hard-to-test systems including scientific models, automated driving systems, and cyberphysical systems. This work has been funded through the EPSRC CITCOM project. More details on this work can be found here. Our Causal Testing Framework is available here.

State Machine Inference and Analysis

I have a longstanding interest in techniques that help to understand the sequential behaviour of systems when a prior model is unavailable. Key contributions in this area include:

Extended Finite State Machine (EFSM) inference — a technique to infer state machines with guards (Journal of Empirical Software Engineering, 2016) and full computational EFSMs with state transition functions (ICSME’16).
LTSDiff — an algorithm to graphically compare two state machines (ACM Transactions on Software Engineering Methodology, 2013).

Second-order uncertainty in Software Engineering

Second-order uncertainty is concerned with quantifying the (un-)certainty surrounding a probability. Recent work has focussed on using Subjective Logic to reason about second-order uncertainty in SE contexts.

Using Evidential Reasoning to quantify second order uncertainty in Safety Arguments ISSRE’15
Using Subjective Logic to reason about uncertainty in Empirical Software Engineering experiments EASE’20
Using Subjective Logic to reason about uncertainty in inferred state machines (IEEE Transactions on Software Engineering, 2023).

Team

On the CITCOM project I am currently working with two fantastic Research Software Engineers - Michael Foster and Farhad Allian.

I am currently supervising the following Ph.D. students:

Giulia Neri is investigating the relationship between organisational factors and exploratory testing.
Harry Bolton is investigating probabilistic test stopping criteria for fuzzing and for cyber-physical testing. Harry is jointly supervised with James Law at the Advanced Manufacturing Research Centre (AMRC).

I have had the priviledge of supervising seven Ph.D. students through to completion throughout my time at Sheffield and Leicester.

Teaching and Administration

Teaching

I am very fortunate to teach topics that are proximate to my research interests. My current topics include:

Software Reengineering (COM3523 / COM6523): A joint undergraduate and masters module, teaching students how to understand and re-engineer unfamiliar, legacy software systems. Delighted to be jointly teaching this with Donghwan Shin.
The Computer Science Ambassadors module: A smaller 3rd year undergraduate module. This involves our 3rd year students engaging with local schools, to try to support and improve their Computer Science provision, with a view towards making Computer Science more inclusive. This is led by my colleague Andy Charlesworth.

Administration

I am currently the school lead on inclusion in Computer Science. In a nutshell, this has a focus on attracting more diverse cohorts of students into Computer Science. This is a partial objective of the Computer Science Ambassador’s module described above. We are also a node in the BCS Levelling Up scheme, where several of our undergraduate students tutor groups of school children to achieve the Maths A-Level (a key entry requirement for most Computer Science courses).