In this paper

a new compact testing named state-difference counting is proposed

and the text confidence for the approach is estimated.The characters of confidence criterion are analysed.At the same time the model of test procedure is created by means of finite state automata.The transformation of the states in the automata is described by use of Markov chains

and the relation between test confidence and sequence length is found.Experiments show that the analysis data agree favourably with the simulation results.