MuJava vs muttest
MuJava
albany.edumuttest
jakubsob.github.ioSide by side
| Figure | MuJava | muttest |
|---|---|---|
| Price from | Free | — |
| Free plan | Yes | — |
| Free trial | — | — |
| Open source | — | — |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| Plans published | 1 | 0 |
| Spec score · Mutation Testing Tools | 8.4 (#3) | 7.1 (#19) |
| Intended users | The maker describes MuJava as a service to the community and says it has been used by students and researchers. | The project describes mutation testing as a way to find weak assertions in test suites, including suites generated with LLMs. |
| License | The project was released as open source under the Apache license in April 2015. | The package is licensed under MIT plus a LICENSE file. |
| Purpose | MuJava automatically generates mutants for Java programs for traditional method-level and class-level mutation testing. | muttest measures test quality by applying small changes to code and checking whether the test suite catches them. |
Plans
In their own words
MuJava
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.
muttest
muttest is a free R package for mutation testing: it changes selected parts of R code and runs tests to measure which changes the test suite catches. Its mutation score reports the percentage of mutations caught, helping identify weak assertions. Users can choose what to change and where, with mutators for operators, boolean and NA or NULL values, function calls, strings, numbers, indexes, conditions, negation, and return values. Presets group common mutation types, including arithmetic, comparison, logical, numeric, string, and condition changes. Examples use testthat and show how changing comparison operators can expose untested boundary cases. Reports are available in HTML and JSON, with feedback on files that may need stronger assertions. Documentation links a guide for running checks in CI, including GitHub Actions, score badges, and thresholds. A July 2026 update describes parallel execution. The package supports Linux, macOS, and Windows, is licensed under MIT plus a LICENSE file, and requires R version 4.1.0 or later according to its CRAN listing.