T-way strategies aim to generate effective test data for detecting fault due to interaction. Different levels of interaction possibilities have been considered as part of existing t-way strategies including that of uniform strength interaction, variable strength interaction as well as input-output based relations. Many t-way strategies have been developed as a result (e.g. GTWay, TConfig, AETG, Jenny and GA for uniform strength interaction; PICT, IPOG and ACS for variable strength interaction; and TVG, Density and ParaOrder for input-output based relations). Although useful, all aforementioned t-way strategies have assumed "sequence-less" interactions amongst input parameters. In the case of reactive system, such an assumption is invalid as some parameter operations (or events) occur in sequence and hence, creating a possibility of bugs or faults triggered by the order (or sequence) of input parameters. If t-way strategies are to be adopted in such a system, there is also a need to support test data generation based on sequence of interactions. In line with such a need, this paper discusses the sequence based t-way testing (termed sequence covering array) as an extension of existing t-way strategies. Additionally, this paper also highlights the current progress and achievements.