Glossary Mutation Testing
Mutation Testing
Also known as:
mutation test, mutantTechTesting
Definition
Deliberately breaking the code in small ways — flip a comparison, drop a branch, change a constant — and running the tests; a mutant that survives is a test suite that would not have noticed
Measures test quality where coverage measures test reach. A line can be 100% covered by a test that asserts nothing about it; mutation testing is how you find that out.
The test of the tests. Coverage tells you a line ran; a mutation score tells you whether a test would have caught it changing. The two disagree more often than people expect, and the disagreement is always in the same direction.