A Study Of Strategies About Testing Safety Critical Software Based On Testing Coverage

Software plays a fatal role in safety critical systems such as aviation system,aerospace system and the military system. Once it becomes invalid, the system will beat dangerous condition or suffer from serious accidents even disasters. Such softwareis called safety critical software whose basic requirement is high reliability.Software testing, as an important means for ensuring quality and reliability ofsoftware, has been under the spotlight. How to cover more defects of the software byexecuting fewer test cases under the urgent conditions is a puzzle confronted bysoftware testing. Measuring the sufficiency and effectiveness of software testing isalso needed to verify the high reliability of the tested safety critical software.The testing coverage is an effective measurement index for the sufficiency andefficiency of testing, and it is closely related to the defects and reliability of thesoftware. In the paper, based on the current research situations, the testing strategiesof safety critical software based on testing coverage are proposed and used to instructtesting the certain safety critical software, which raised the efficiency of testing andthe reliability of safety critical software.This paper mainly makes the following contributions:â… .The testing strategies about testing safety critical software based on testingcoverage are proposed. The main idea of the testing strategies is generating the test cases by Black-box testing, and choosing the test cases contributing to testingcoverage according to its growth rate, and predicting defects remained in the softwarewith the help of the information about testing coverage and the discovered defects,and replenishing the test cases at pertinence after analyzing the properties and thesocial phenomenon of defects.â…¡.After studying how to instruct the software testing with the help of the testingcoverage, the concept of the contribution of test cases to testing coverage is proposed,and the general forms of the growth function of testing coverage is given bymathematical methods, and the enhanced Inflection-S testing coverage function isproposed, which is verified by the test data issued by NASA. The results show thatthe enhanced Inflection-S testing coverage function proposed in the paper has thebetter fitting accuracy than the existing testing coverage functions, and is moreconsistent with the growth of the testing coverage in the real testing work.â…¢.The paper studies the relationship between the testing coverage and thedefects of softwares. In order to make full use of the testing coverage, the predictionmodels for software defects based on the time distribution are studied, and theprediction models for software defects are proposed based on it. And it is verified bythe data of the testing coverage and the software defects issued by NASA and ESA.The results show that the enhanced Inflection-S testing coverage function proposedin the paper is more stable and more consistent with the actual number of the defects.â…£.The experiments are combined with the test tasks of the certain space software,and the theoretical researches are applied to instruct the real test tasks. The resultsshow that the testing strategies about safety critical software based on testingcoverage proposed in the paper are able to raise the efficiency of testing, and discoverthe more defects existing in the software by executing the fewer test cases under theurgent conditions, and finish the testing tasks more effectively and efficiently.