Cosmic Ray

Cosmic Ray is a mutation testing tool for Python 3. It makes small changes to the source code and runs the test suite for each one, to find code whose behaviour is not checked by the tests.

A mutation testing session is configured in a file and stored in a session database, so that long runs can be interrupted and resumed. Mutations can be executed locally or distributed over several workers, and reports show the surviving mutants. The tool works with any test runner that can be started from the command line, such as pytest or unittest.

Cosmic Ray is free and open source under the MIT licence.