MuJava vs Mutant

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.

Mutant is Ruby mutation-testing software that changes code in controlled ways to check whether tests catch the changes. It alters arithmetic, logical and bitwise operators, removes statements, and changes return values. It works with RSpec, Minitest and Test::Unit, and supports incremental runs for CI. Supported Ruby versions are 3.2, 3.3, 3.4 and 4.0 for runtime, syntax and mutations. Rails support is verified for versions 7.2, 8.0 and 8.1, with parallel-worker database isolation for PostgreSQL and SQLite. Mutant runs on developers’ machines or in CI, and includes parallel execution and reports of surviving mutants. It cannot generate mutations for methods defined inside closures, including methods created with module_eval, class_eval, define_method or define_singleton_method. The open-source plan is free for public repositories with the full feature set. Commercial monthly pricing is $30 a month per developer; yearly pricing is $250 a year per developer. CI use requires no additional subscriptions.