Model-based testing (MBT) offers various methods for improving software quality through efficient test design, with stateless and stateful models being two primary approaches. Stateless MBT, widely used in the industry, models business processes without considering states, making it easy to apply but limited in detecting complex bugs, as it often requires coding for constraints and guard conditions to avoid infeasible paths. Conversely, stateful MBT focuses on state transitions, which can handle complex systems better by identifying tricky bugs but demands more coding effort, particularly in defining states and transitions, which can be error-prone and time-consuming. Despite the strengths and weaknesses of both methods, neither is deemed entirely satisfactory, as a third category, the 'aggregate' MBT, promises to address these issues more effectively. The next blog will explore this method further.