Regression testing, which plays an important role in software maintenance, usually relies on test adequacy criteria to select and prioritize test cases. However, with the wide use and reuse of black-box components, such as reusable class libraries and COTS components, it is challenging to establish test adequacy criteria for testing software systems built on components whose source code is not available. Without source code or detailed documents, the misunderstanding between the system integrators and component providers has become a main factor of causing faults in component-based software. In this paper, we apply mutation on interface contracts, which can describe the rights and obligations between component users and providers, to simulate the faults that may occur in this way of software development. The mutation adequacy score for killing the mutants of interface contracts can serve as a test adequacy criterion. We performed an experimental study on three subject systems to evaluate the proposed approach together with four other existing criteria. The experimental results show that our adequacy criterion is helpful for both selecting good-quality test cases and scheduling test cases in an order of exposing faults quickly in regression testing of component-based software.

Software testing is an important technique for assurance of software quality. Mutation testing has been identified as a powerful fault-based technique for unit testing, and there has been some research on automatic generation of test data for mutation testing. However, existing approaches to this kind of test data generation usually generate test data according to one mutant at one time. Thus, more test data that are needed for achieving a given mutation score. In this paper, we propose a new approach to generating one test data according to multiple mutants that are mutated at the same location at one time. Thus, our approach can generate smaller test suite that can achieve the same mutation testing score. To evaluate our approach, we implemented a prototype tool based on our approach and carried out some preliminary experiments. The experimental results show that our approach is more cost-effective.