PIT (Pitest)

PIT, also called Pitest, is a mutation testing system for Java and the JVM. It seeds small faults, called mutations, into the application code and runs the unit tests against each modified version. If a test fails, the mutation is killed; if all tests pass, the mutation survived, which reveals code that is executed by the tests but not really checked.

PIT integrates with Maven, Gradle and Ant, and works with test frameworks such as JUnit and TestNG. Its reports combine line coverage and mutation coverage in one view, showing which lines are tested and which faults go undetected. It is designed to be fast, and its authors recommend running it frequently, focusing on the code that has changed.

PIT is free and open source under the Apache 2.0 licence. Commercial extensions are offered as Arcmutate.