Authentication Test is a new type of analysis and design method of security protocols based on Strand space model, and it can be used for most types of the security protocols. However, as a Strand space model, it is inclined to be used for the proof of correctness, and is relatively weaker for incorrectness analysis. This paper proposes the concepts of Enhanced Authentication Test (EAT) and the correspondence function that can solve the problem. Compared with the original concept, the new approach is more formal and can make protocol analysis easier both by hand and automatically.