Test Case Generation Based On Colored Petri Net And Its Application In Train Control System

With the continuous development of China's railway, CTCS (Chinese Train Control System) is proposed based on national situations. CTCS mainly refers to the standards of European ETCS, and it improves the efficiency of train operations, but it also requires a higher security-related technology, such as the testing technology for the system.Testing is an important process before the CTCS-3 being put into practice and is an essential way to ensure the safe operations of the train and improve the efficiency of the capacity of transporting.Based on software testing methods and knowledge of Petri nets, an approach to generating test cases based on CPN is proposed and is applied to RBC switch to find out whether the functions of on-board equipment is consistent with the specifications. The main work of this paper is as follows:1. The testing situation on train control system is introduced, and it is mainly about a hybrid testing method and its application in foreign countries and the principles of generating test cases and the methods of designing test sequences on testing the functions of on-board equipment of CTCS-3. And then, the development of train control system at home and abroad and CTCS-3 are presented.2. There are different kinds of testing methods depending on different standards. For example, it can be divided into black-box testing method, white-box testing method and grey-box testing method according to the standard of testing technology. Detailed introduction of black-box testing method and white-box testing method is introduced in the following section of this chapter.3. By comparing the meanings of partial path coverage and complete path coverage, a testing method based on complete path coverage is put forward; On the basis of the definition of Petri nets, the approaches to constructing reachability graph, reachability trees and coverability trees are proposed; Combining the complete path coverage testing method, breadth-first search and the approaches to constructing reachability graph, reachability trees, and coverability trees, the design of generating test cases based on CPN is fulfilled.4. According to the specifications for RBC-RBC interface of CTCS-3, the main steps of RBC switch are summarized and a sequence diagram is drawn by UML. Different states for Handing over RBC, Accepting RBC and on-board equipment are defined based on the sequence diagram, and a state diagram of Handing over RBC, Accepting RBC and on-board equipment is drawn. Using CPN Tools and the existed state diagram, the hierarchical CPN models of RBC switch are modeled. Based on the behavior properties of the CPN models and the method of testing cases presented above, a test path and a test case is generated. The valuation to the generated test path and test case is made and a conclusion that the method of generating test cases based on CPN is correct is drawn at last.5. The correlative ways to solve the problem that test case generation based on a complex CPN model are presented and future research is reviewed in the end.