MuJava vs pymute

MuJava is a free, open-source tool for mutation testing of Java programs. It generates mutants for individual classes and packages, using 24 class-level operators as well as method-level operators, then runs tests against those mutants and evaluates mutation coverage. Tests must be JUnit test cases with public test classes and methods that call the classes under test; JUnit test suites are not supported. Equivalent mutants require manual identification, and the documentation says they typically make up 5% to 20% of mutants. Version 4 supports Java 1.6 language features, including generics, annotations, enumerations, varargs, enhanced for-each loops and static imports. Setup uses two JAR files and a configuration file, with Java CLASSPATH and PATH configuration. The documented workflow uses Java GUI applications; a command-line interface called muScript was released in March 2014, and an Eclipse plugin was created in 2007. The project is provided as-is, without guarantees of answers, repairs or improvements. It is available for Linux, macOS and Windows.

pymute is a free mutation testing tool for Python projects using pytest or tox, written in Rust. It creates a temporary directory for each mutant and changes Python file text rather than operating on the abstract syntax tree. Pytest is the default runner, and documented mutation types include math operators, conjunctions, booleans, control flow, comparisons and numbers. By default, it reports mutants that survive because tests pass; other output levels can show caught mutants or process output. Options let users filter modules with a glob, select tests and mutation types, set thread count and cap the number of mutants. That cap runs a randomly selected subset. Installation uses Cargo from crates.io or GitHub and requires Rust and Cargo. With pytest, tests need to run from the project root in independent copies and exercise the local copy rather than an installed package. Tox sets up a separate environment and installs the package for each mutant, which the project describes as considerably slower. Parallel threads each need temporary disk space, and a run may fail if /tmp runs out. The repository identifies its license as Unlicense.