1. A method of generating a sequence of instructions and arguments for testing a processor, including: providing a fuzzy finite state machine having a plurality of states corresponding to different instructions and/or arguments, wherein each state can be followed by any of a number of the plurality of states, each state having a set of weights defining the probability of at least one random decision for each state, wherein the at least one random decision includes the decision as to the following state; selecting a first state; making the or each random decision for the state in accordance with the weights to generate corresponding instructions and/or arguments and to determine the next state; repeating the step of making the or each random decision to generate a sequence of instructions and/or arguments randomly in accordance with the weights; adapting the weights based on the resulting sequence; and repeating the steps of generating a sequence of instructions in order to generate a plurality of sequences covering predetermined test requirements.