junit-quickcheck

QuickcCheck-type tools (generators for tests that know about the edge cases of a domain - e. g. for the domain of numbers considering things like 0, the infinities, various almost-and-just-over powers of two, NaN and mantissas for floats, etc.): * QuickCheck: https://hackage.haskell.org/package/QuickCheck * Hypothesis: https://hypothesis.readthedocs.io/en/latest/ * JUnit QuickCheck: https://github.com/pholser/junit-quickcheck Fuzz testing tools (tools which mutate the inputs to a program in order to find interesting / failing states in that program). Generally paired with code coverage: * American Fuzzy Lop (AFL): https://github.com/google/AFL * JQF: https://github.com/rohanpadhye/JQF Mutation / Fault based test tools (review your existing unit coverage and try to introduce changes to your _production_ code that none of your tests catch)

If you want an easy way to have better mutation coverage, check out property based testing. Eg junit-quickcheck for Java. https://github.com/pholser/junit-quickcheck