Research On Combinatorial Test Case Reduction And Implementation Method Of CTCS-2 Onboard Equipment

Chinese Train Control System-Level 2(CTCS-2)is an important part of the Chinese high-speed railway signal system,which can ensure the safe and efficient operation of trains.As one of the core equipment of the train control system,the onboard equipment undertakes the safety functions of monitoring the train speed and preventing the train from crossing the end of authority.Once the function fails,it may cause serious traffic accidents.Therefore,it is necessary to conduct thorough tests on the onboard equipment to ensure that the onboard equipment can meet the safety requirements in various scenarios.Due to a large number of interactive information,complex interfaces,and a large number of combinations of information in the onboard equipment software,there are different combinations of input information,which cover various input conditions that may lead to software failure.The use of exhaustive combination is often easy to cause the explosion of test space,resulting in the infeasibility of the test.Therefore,how to ensure the rapid and effective test of various input combinations is particularly important.Combinatorial testing focuses on the system input model and analyzes the interactive combination of all input information affecting the system,which can simplify the scale of the test set and improve the test efficiency on the premise of ensuring the combination coverage.However,there are many problems in the research of onboard equipment combinatorial testing optimization.On the one hand,when reducing multiple combinatorial test sets,the security requirements of test scenarios corresponding to different test sets are not considered.On the other hand,the implementation process of abstract tests is cumbersome and the time cost of manual implementation is high.To solve the above problems,this thesis studies the reduction and implementation of the onboard equipment combinatorial test set.The main contents are as follows.(1)The security of the test scenario is applied to the process of test reduction,and a combinatorial test case reduction method based on scenario security is proposed.This method uses HAZOP and the risk matrix method to evaluate the safety level of the test scenario.The GRE and Ant Colony Optimization based on requirement coverage are improved.On the premise of ensuring the combinatorial coverage,retain the tests in the high-security scenario,reduce the redundant tests in the low-security scenario,and decrease the execution cost of the test set as much as possible.The results show that the combination of improved GRE and Ant Colony Optimization can effectively remove the low-security redundant tests and decrease the test cost.(2)The method of implementing combinatorial tests as test cases and test scripts is studied,and an implementation method based on a relational mapping table is proposed.This method first extracts the feature items of test cases and test scripts,then implements the equivalent class of combinatorial testing parameters,and establishes the relationship between the value of the equivalent class and feature items,that is,test-case and test-script relationship mapping tables.The parameter implementation results are mapped to cases and script documents through the relationship mapping table to realize the implementation of tests.(3)The auxiliary tool of combinatorial test reduction and implementation is designed.The tool can import the information of combinatorial test sets,use three algorithms for case reduction,edit the information of test cases and test scripts,and automatically generate test cases and test scripts.It reduces the difficulty of manually compiling cases and scripts,and effectively improves test efficiency.