mutatest

mutatest is a mutation testing tool for Python that checks whether a test suite detects small modifications, called mutations, of the source code.

It modifies the abstract syntax tree in memory instead of rewriting source files, and uses the compiled bytecode cache to run the tests against each mutant. It can sample mutation locations at random and run in parallel to limit execution time, and it reports the surviving mutants so that missing tests can be identified.

mutatest is free and open source under the MIT licence. Its code has not changed since February 2023.