To assess the quality of test suites, mutation analysis seeds artificial defects (mutations) into programs; a nondetected mutation indicates a weakness in the test suite. We present an automated approach to generate unit tests that detect these mutations for object-oriented classes. This has two advantages: First, the resulting test suite is optimized towards finding defects modeled by mutation operators rather than covering code. Second, the state change caused by mutations induces oracles

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... precisely detect the mutants. Evaluated on 10 open source libraries, our µTEST prototype generates test suites that find significantly more seeded defects than the original manually written test suites.