Interaction sequences (ISeqs) are an abstraction of interactive systems which allow us to inspect the interactive system behaviour. In this research, ISeqs are used to support interactive system testing. In interactive system testing the components of an interactive system, the functional and the interactive, are often tested separately. However, errors can still occur when these components overlap. Therefore, we must investigate ways to test this overlap as part of a more comprehensive testing approach. ISeqs provide a clear view of this overlap, which we use to inform a model-based testing approach. By testing not only the functional and interactive components of a system, but also this overlap, ISeqs provide us with a way to better cover the interactive system state space, improving system reliability and safety.