Research On Automatic Test Method For Route Control Function Of Railway Signalling Interlocking Software

The computer interlocking system is a critical system demanding high safety and reliability in railway transportation.It is a vital task to improve the quality of software under the premise that the hardware is safe and reliable.Therefore,how to test the interlocking software effectively has become a subject worthy of study.The traditional test method depends on designing and executing test cases manually.This method is time-costing and the test results are affected by human factors,so it is difficult to test sufficiently.At the same time,the pair wise test has become a hot research field in black box testing because of its high efficiency and reliability.However,the general algorithm of pair wise testing is devoted to reduce the size of test suites,without considering the fact that the interface devices of interlocking system may need a weight parameter for actual requirement.In view of the above situation,this paper presents an automatic test method that combines two aspects by taking the advantage of traditional test cases and using the efficiency advantage of pair wise test method.The main work of the paper is as follows:(1)The test requirements of interlocking software are analyzed,and the test cases used in traditional testing are reorganized to 11 test items suitable for automatic testing.Through the analysis of different objectives in test items about setting routes and changing states of equipment,the strategy of applying the pair wise test method is to increase test coverage and to improve test efficiency.(2)This paper presents an automatic generation method of interlocking software test cases based on improved IPO(In-Parameter-Order)algorithm.There are two main ideas:one is the introduction of weight parameters in the original algorithm,which will affect the test case generation order and combination to make some important parameters appear more frequently in test cases under current test scenario.The other is the analysis about reasons of errors according to test results,which will feedback to weight parameters to optimize the quality of test cases.So they will be more efficient to find errors of interlocking software.(3)The execution process of the automatic test program is designed in detail,which covers functions and safety protection requirements such as setting routes,operating equipment,closing and reopening signals and releasing routes.By organizing test sequences,the repeat operation is reduced to less than half of the original process.(4)The automatic test environment is built,and UDP communication is used to complete the data interaction between interlocking software,simulator and test program.The test result of a specific station shows that compared with traditional testing,the automatic test method can find more errors.Time spent in testing is reduced by more than 37%.The detecting ability and detection speed of some test cases is also improved.The result of research work in this paper indicates that this automatic test method for interlocking system not only increases test coverage,but also improves test efficiency.In addition,the ability and speed to detect errors of some test cases has also been improved.On the whole there is an obvious improvement compared with traditional manual test method.