go-mutesting vs Infection

go-mutesting is a framework for mutation testing Go code to identify parts of a program that tests may not cover. It changes source code in controlled ways, runs tests, and reports whether each mutation is killed or survives; surviving mutations are accompanied by a source patch. Its mutation score reflects the share of generated mutations killed by the test suite. Targets may be Go files, directories, or packages, including recursive `...` patterns, while `_test` files are excluded. By default, it replaces the original file with a mutation and runs that package’s tests. Alternatively, an external command can test each mutation, with environment variables describing the change and exit codes indicating the result. Built-in mutators cover branches, comparisons, boolean expressions, statement removal, and Cosmos SDK arithmetic and comparisons. Custom mutators can be registered through the Mutator interface. The MIT-licensed tool is free and runs on Linux or in self-hosted environments. Its README positions mutation testing as a supplement to automatic test suites and cautions that false positives can occur.

Infection is a PHP mutation-testing library that shows which changes a test suite fails to detect. It creates mutants using predefined operators, runs tests against changed code, and records killed and escaped mutants, errors, and timeouts. Its Mutation Score Indicator measures the share of generated mutations detected by tests; it also reports Mutation Code Coverage and Covered Code Mutation Score Indicator. Infection supports PHPUnit, PhpSpec, Codeception, and Testo, and runs from the command line at a project root. Teams can run mutated tests in parallel, focus analysis on touched lines or files, and set minimum mutation-score thresholds that fail a build. The homepage describes more than 100 mutators grouped into profiles and allows custom mutators. Optional PHPStan and Mago integrations can help catch escaped mutants involving type violations, dead code, and unreachable paths. Installation options include PHAR, Phive, Composer, Git, and Homebrew. A browser playground supports trying PHP code and tests without installing the tools. Infection is free under the BSD-3-Clause license and requires PHP 8.3 or newer plus Xdebug, phpdbg, or pcov.