Do you know a reference (freely available on the web) where the likelihood ratio test is applied in order to test for the Markov property?
The setting is a directly observable discrete Markov-chain with given transition matrices. The concrete application is a model for credit rating transitions. Some statistical tests are applied in this paper Time series properties of a rating system based on financial ratios but there are too little details.
Evaluating the Markov property by Frank Bickenbach and Eckhardt Bode is an example for testing the Markov property but it is behind a pay wall.
EDIT: The concrete test is: Null hypothesis: rating transitions do not depend on past rating distributions. The alternative hypothesis: rating transitions depend on past rating distributions (in the sense of a 1st order Markov chain).