The care and feeding of wild-caught mutants

Mutation testing of a test suite and a program provides a way to measure the quality of the test suite. In essence, mutation testing is a form of sensitivity testing: by running mutated versions of the program against the test suite, mutation testing measures the suite's sensitivity for detecting bugs that a programmer might introduce into the program. This paper introduces a technique to improve mutation testing that we call wild-caught mutants; it provides a method for creating potential faults that are more closely coupled with changes made by actual programmers. This technique allows the mutation tester to have more certainty that the test suite is sensitive to the kind of changes that have been observed to have been made by programmers in real-world cases.