Research On Test Case Generation Method Of CTCS-2 Train Control System DFSM-based

Train control system is a core component of the modern railway signal system,which ensures the safe and efficient operation of the train.Studying the test methods in train control system is of great significance for improving its reliability.The test method based on the deterministic finite state machine(DFSM)uses the DFSM model to describe the requirements of the function under test,and uses the test case generation method to generate test cases from the DFSM.This paper takes the CTCS-2 train control system as the research object,studies the method of test path generation and the method of test path instantiation based on DFSM,and gives the automatic generation methods.This paper designs a method of test path generation based on the minimum test cost transition coverage criteria.First,parse the model to get model information,and generate sequences that satisfy the advanced transition coverage criteria.Next,generate sequences that satisfy the minimum test cost transition coverage criteria and convert sequences into test paths.Finally,using the case in train control system testing,demonstrate the specific steps of the generation of test paths.Compared with the test paths which is generated by the algorithm of breadth-first to satisfy transition coverage criteria,it shows that the test paths generated by this method has fewer redundancy and the number of paths is smaller,thus effectively reducing the test cost.In order to instantiate the test path into concrete test cases,this paper proposes a method combining logical coverage and input space partition.First,according to logical expressions of the transition conditions in the model,generate the combinations of logical values in the clauses that meet the logic coverage criteria.Secondly,partition the input space of the input variables in the expressions,and generate the value set of each variable.Then,considering the logical value combinations of the clauses as a constraint,calculate variables' test input subsets that satisfy the constraint,and combine the test input subsets of the variables to generate the concrete test cases which are related to the interface of the model of function.Finally,use a basic example to illustrate the feasibility of the method.Finally,taking CTCS-0/CTCS-2 level transition function for on-board equipment in CTCS-2 train control system as an example,first analyze the requirements,summarize the normal transition scene and special transition scene of the function.Then,build the DFSM model and apply it to the test path generation method and the test case generation method of this paper to get the test paths and the test cases.These results show that the methods can cover more complete functional requirements with higher efficiency.