Mutation Testing

2 articles

Software Engineering 08 Sep 2026 9 min read

Use Mutation Testing to Find Weak Tests

A test suite can execute every line of an important function and still fail to detect that the function is wrong. Coverage tells you which code ran. It does not tell you whether the assertions would notice a meaningful defect in that code. Mutation testing approaches the problem from the other direction. A mutation testing tool makes small, deliberate changes to production code and runs the tests. If the tests fail, they detected the change. If the tests still pass, the altered behavior has exposed a possible weakness in the suite.

Software Engineering Testing

Software Engineering 03 Sep 2026 7 min read

Mutation Testing for Stronger Test Suites

A test suite can execute every important line of code and still miss serious defects. Coverage tells you which code ran, but it does not tell you whether the tests would notice if that code behaved incorrectly. Mutation testing examines that gap. It makes small, systematic changes to production code and runs the tests against each changed version. If the tests fail, the mutation is killed. If they still pass, the mutation survives and points to a place where the suite may not distinguish correct behaviour from incorrect behaviour.

Software Engineering Testing