Requirement dependencies-based formal approach for test case prioritization in regression testing

Regression testing is the testing activity performed after changes occurred on software. Its aim is to increase confidence that achieved software adjustments have no negative impact on the already functional parts of the software. Test case prioritization is one technique that could be applied in regression testing with the aim to find faults early, resulting in reduced cost and shorten time of testing activities. Thus, prioritizing in the context of regression testing means to re-order test cases such that high priority ones are run first. The current paper addresses the test case prioritization as a consistent part of a larger approach on regression testing, which combines both test case prioritization and test case selection in order to overcome the limitations of each of them. A comprehensive formalization of test case prioritization is provided, incorporating beside the well known ingredients (test case, test requirement, fault, cost) also elements relating to the functional requirements and dependencies between requirements. An evolutionary algorithm is used to construct the re-ordering of test cases, considering as optimization objectives fault detection and cost. A synthetic case study was used to empirically prove our perspective for test case prioritization approach.