Pitest

PITest is a Java mutation testing tool that integrates well with build tools (such as Maven, Gradle, and Ant) and test frameworks (such as JUnit, TestNG, and Spock).

PITest can generate mutants at the bytecode level, which makes it faster and more accurate than source-code level mutation tools. It supports various mutation operators, such as arithmetic, conditional, method call, and return value substitutions.

The tool also provides a rich set of reports and metrics that help analyze the test results and identify improvement areas.

Pitest runs your unit tests against automatically modified versions of your application code. When the application code changes, it should produce different results and cause the unit tests to fail. If a unit test does not fail in this situation, it may indicate an issue with the test suite.