Mutatest

6.9easy start · #3 of 25
in Mutation Testing Tools

Free to practise onyes
Free trialnot on record
Well documentedyes
Runs where you workyes

Runs on Linux, Mac, Windows.

Mutatest is ranked #3 of 25 in mutation testing tools on The Geeks Club. It runs on Linux, macOS, Windows. There is a free plan.

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Mutatest Free Free and open source under the MIT License mutatest.readthedocs.io · 2 Oct 2026

Compared on mutation testing tools

Free plan: Yes
Supported languages: Python
Test frameworks: pytest
Parallel execution: Yes
Surviving mutant reports: Yes
Mutation quality gate: Yes
Mutation operators: AugAssign; BinOp; bitwise comparison; bitwise shift; BoolOp; Compare; Compare In; Compare Is; If; Index; NameConstant; Slice

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The record

Purpose: Mutatest is a diagnostic command-line tool for assessing test coverage by checking whether tests detect small code mutations.
Mutation method: It uses Python’s Abstract Syntax Tree grammar to produce valid mutants and changes local __pycache__ files instead of source files.
Coverage: When coverage data is available, mutation targets can be restricted to lines marked as covered.
Sampling: It randomly samples mutation locations and potential mutations, and a random seed can make trials reproducible.
Controls: The command line supports run modes, mutation category selection, file exclusions, timeouts, output reports, and survivor thresholds.
API: Mutatest includes an API for custom mutation controls.
Integrations: The documentation describes running test commands such as pytest and using coverage data to filter mutation targets.
CI use: Mutatest can raise an exception when surviving mutants meet a configured threshold, for use in automated runs such as a continuous integration stage.
Platform support: The project says it was tested on Linux, Windows, and MacOS with Azure pipelines.
Python support: The installation documentation requires Python 3.7 or Python 3.8.
Known limitation: The documentation warns that repeated test-suite runs can make mutation testing slow, so it is intended as a diagnostic tool rather than a run over an entire codebase on every commit.
Test runner limitation: Although a test command can be supplied, the documentation says only pytest has been tested to date.
Support: The project directs users to its GitHub issue tracker to submit bugs or request features.
Price from: Free

Where it ranks on The Geeks Club

Best Mutation Testing Tools in 2026#3 of 25

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Sources

mutatest.readthedocs.io/en/latest/· checked 2 Oct 2026
mutatest.readthedocs.io/en/latest/install.html· checked 2 Oct 2026
mutatest.readthedocs.io/en/latest/commandline.html· checked 2 Oct 2026
github.com/EvanKepner/mutatest· checked 2 Oct 2026
mutatest.readthedocs.io/en/latest/license.html· checked 2 Oct 2026