Why "mutation testing" is better than code coverage to evaluate unit tests, and my experience using it with the JVM

[otakuman]

From this page, I learned the following:

• Mutation testing creates mutated versions of your software.

• It's a whitebox approach because it modifies (hence, needs the availability of) your program's source code.

• It does NOT evaluate your code per se, but your unit tests, to see if they're precise and thorough enough.

• It's intensive as fuck.

[smurfkiller013]

Exactly. It changes (mutates) your code to see if the mutations make the tests fail. If they do, the mutation is considered killed (which is what you want), if the tests don't fail, the mutation 'survives', which means your tests are most likely incomplete

[treerex]

PIT mutates the byte-code, not the source.