Search-based mutant selection for efficient test suite improvement: Evaluation and results.

•Evolutionary Mutation Testing (EMT) selects useful mutants for enhancing test suites.•EMT learns the most interesting mutation operators and locations in the code.•Reduced subsets of mutants selected with EMT can lead to noticeable improvements.•EMT works better in complex programs and with well-designed test suites.•The level of test suite refinement allows an accurate estimation of the performance.