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With the increasing complexity of embedded satellite platform software, one of the main challenges of software test is how to choose effective testing strategy and how to select a small number of test cases from the huge test case space in order to shorten on-board software development cycle. In response to the current problems of low efficiency and insufficient test coverage in test case design, this paper proposes a method of using dynamic fault tree models to construct equivalent classes for test case design. Firstly, based on fault propagation path and its decision mode of the dynamic run profile and timing sequence of the embedded on-board system, dynamic fault tree model of whole satellite on-board software system must be established. Secondly, the dynamic fault tree is used as the test case design tree, and a certain search and simplification strategy is used to generate minimum cut sequence sets. By the set theory and equivalent class rules, triggering conditions that meet the occurrence of fault path nodes are considered as input of the test case. The resultant status nodes are used as the expected output. After dynamically loading the test case input, the actual response results of the software are judged by consistency with the expected results. Finally, a test experiment analysis was conducted using satellite navigation positioning and orbit calculation submodule of on-board system software. The dynamic fault tree model was established by constructing the operational task profile of orbit processing, so test cases were designed by simplified cut sequence set. The results show that using this method for test case design can greatly optimize the set of test cases. While ensuring coverage and adequacy, compared with traditional TestBed software tools without regard to software task profile, the testing efficiency was improved by about 28%.
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