PIT Mutation Testing

Quick reference

The maven command to run pitest is:

• mvn clean test org.pitest:pitest-maven:mutationCoverage

Introduction

How do we know whether a test suite for a piece of software is any good?

One way is with code coverage testing, but this is of limited use.

• Test coverage can definitely show you what you are not testing.
• It isn’t very effective at showing whether you are testing well the things that you are testing.

For that, we have mutation testing. Mutation testing involves:

• making many copies of the solution (which is assumed to be correct)
• turning these copies into mutants (copies of the solution with bugs in them)
• checking to see whether those bugs are caught (are the mutants killed?)

One tool for mutation testing in Java is PIT Test, which is explained at https://pitest.org

See also

• Discussion of Mutation testing in https://ucsb-cs156.github.io/tutorials/student_ex08/
• Baeldung Article: https://www.baeldung.com/java-mutation-testing-with-pitest

---