Infection

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Output—per 1M tokens

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About

Infection is ranked #3 of 25 in mutation testing tools on Inferse. It runs on Linux, macOS, Web.

Compared on mutation testing tools

Free plan: Yesinfection.github.io
Supported languages: PHPinfection.github.io
Test frameworks: PHPUnit, PhpSpec, Codeception, Testoinfection.github.io
Incremental analysis: Yesinfection.github.io
Parallel execution: Yesinfection.github.io
Surviving mutant reports: Yesinfection.github.io
Mutation quality gate: Yesinfection.github.io
Mutation operators: Arithmetic, boolean, cast, conditional boundary, conditional negotiation, equality, function signature, nullify, number, operator, regex, removal, return value, visibility, and unwrap mutatorsinfection.github.io

Facts

Purpose: Infection mutates PHP source code and reports which changes a test suite fails to catch.infection.github.io · 30 Sept 2026
Testing method: It is a PHP mutation-testing library based on abstract-syntax-tree mutations and runs as a CLI tool from a project root.infection.github.io · 30 Sept 2026
Test frameworks: Supported test frameworks are PHPUnit, PhpSpec, Codeception and Testo.infection.github.io · 30 Sept 2026
Runtime requirements: The current documentation requires PHP 8.3 or newer and Xdebug, phpdbg or pcov.infection.github.io · 30 Sept 2026
Mutation metrics: Infection provides Mutation Score Indicator, Mutation Code Coverage and Covered Code Mutation Score Indicator metrics.infection.github.io · 30 Sept 2026
CI thresholds: The --min-msi and --min-covered-msi options can fail a build when configured mutation scores are not reached.infection.github.io · 30 Sept 2026
Parallel execution: Tests for mutated code can run in parallel with the --threads option, including automatic CPU-core detection with --threads=max.infection.github.io · 30 Sept 2026
Changed-code mode: The --git-diff-lines option mutates only touched lines, and --git-diff-filter can restrict mutation to changed files.infection.github.io · 30 Sept 2026
Mutators: The homepage describes more than 100 mutators grouped into profiles, plus custom mutator support.infection.github.io · 30 Sept 2026
Static analysis: Infection supports optional PHPStan and Mago integrations to catch escaped mutants involving type violations, dead code and unreachable paths.infection.github.io · 30 Sept 2026
Cloud reporting: Infection can send mutation badges and HTML reports to Stryker Dashboard using a project API key.infection.github.io · 30 Sept 2026
Distribution: The recommended PHAR distribution bundles PHPUnit, PhpSpec, Codeception and Testo, and the PHAR signature can be verified with the documented GPG key.infection.github.io · 30 Sept 2026
License: The project is released under the BSD-3-Clause license.infection.github.io · 30 Sept 2026
Security policy: Only the latest Infection version is supported under its security policy, although older versions may be patched depending on vulnerability severity; vulnerabilities should be reported privately on GitHub.github.com · 30 Sept 2026
Community support: The project links to Discord and GitHub Discussions for community help and states that it welcomes pull requests and issues.github.com · 30 Sept 2026
Purpose: Infection mutates PHP source code and reports changes that a test suite fails to catch.infection.github.io · 2 Oct 2026
How it works: It creates mutants using predefined mutation operators, runs tests covering changed lines, and records killed or escaped mutants, errors, and timeouts.infection.github.io · 2 Oct 2026
Mutation score: It reports a Mutation Score Indicator (MSI) that measures the percentage of generated mutations detected by the tests.infection.github.io · 2 Oct 2026
Test frameworks: It supports PHPUnit, PhpSpec, Codeception, and Testo.infection.github.io · 2 Oct 2026
Runtime requirements: The current guide says Infection requires PHP 8.3 or later and Xdebug, phpdbg, or pcov installed.infection.github.io · 2 Oct 2026
Mutators: The homepage describes more than 100 mutators, grouped into profiles, and support for custom mutators.infection.github.io · 2 Oct 2026
CI thresholds: The --min-msi and --min-covered-msi options can fail a build when the configured mutation-score threshold is not met.infection.github.io · 2 Oct 2026
CI reports: Infection can emit GitHub annotations and GitLab Code Quality reports, and can publish mutation badges and HTML reports through Stryker Dashboard.infection.github.io · 2 Oct 2026
Static analysis: The documentation describes integration with PHPStan, Psalm, and other static analysis tools.infection.github.io · 2 Oct 2026
Installation: The maker documents PHAR, Phive, Composer, Git, and Homebrew installation methods.infection.github.io · 2 Oct 2026
Security: The maker says its PHAR distribution is signed with a GPG key and documents how to verify the signature and fingerprint.infection.github.io · 2 Oct 2026
Browser playground: The Infection Playground lets users write PHP code and tests in a browser and run mutation testing without installing Composer, Infection, or PHPUnit.infection.github.io · 2 Oct 2026
Caveat: The command-line guide warns that parallel runs can produce false positives when tests depend on one another or use a database.infection.github.io · 2 Oct 2026
License: The project is released under the BSD-3-Clause License.infection.github.io · 2 Oct 2026