cargo-mutants

cargo-mutants helps improve the quality of a Rust program by finding places where bugs could be inserted without causing any test to fail. Coverage tells which code is reached by a test, while mutation testing tells whether the tests really check the behaviour of that code.

It is a Cargo subcommand designed to be easy to run on any Rust source tree, without changes to the code. It replaces function bodies and operators with alternative values, builds and tests each mutant, and reports the ones that were missed. Runs can be limited to the code changed in a diff, parallelised and used as a check in CI.

cargo-mutants is free and open source under the MIT licence.