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MutPy

MutPy is a free, open-source mutation testing tool for Python source code that helps developers check whether their tests detect changes.

Place
#8 of 25
Score
6.2
MutPy's website

What MutPy is

MutPy is a free, open-source mutation testing tool for Python source code that helps developers check whether their tests detect changes. It applies mutations at the abstract syntax tree level and runs tests to identify changes that go undetected. The default test runner is unittest; pytest support is experimental. MutPy can generate YAML and HTML reports, analyze code coverage, and limit mutations to covered code. It also supports higher order mutations, and command-line options let users select or disable operators and sample a percentage of mutants. The project includes standard and experimental mutation operators. Its README describes support for Python 3.3 and later, and installation is documented through pip from PyPI or from repository source. MutPy is licensed under Apache License 2.0. The README warns that disabling stdout can damage tests that interact with sys.stdout. PyPI lists version 0.6.1, released November 17, 2019, as the latest release. The repository has an Issues section, but no support service or security certification is stated.

Good

  • Applies mutations at the AST level.
  • Generates YAML and HTML reports.
  • Can restrict mutations to covered code.
  • Supports higher order mutations.
  • Offers operator selection and mutant sampling.

Watch out

  • pytest support is experimental.
  • README describes compatibility with Python 3.3 and later.
  • Latest listed PyPI release is version 0.6.1 from 2019.
  • Disabling stdout can harm tests that use sys.stdout.

Who it suits

MutPy suits developers and software testers who want to assess Python tests through mutation testing. It is especially relevant to projects using unittest; pytest users should account for its experimental status.

Verdict

MutPy offers mutation controls, coverage analysis, and report generation for Python testing. Its experimental pytest runner and listed release history are worth considering before adopting it.

Plans and prices

From MutPy's own pricing page, checked 9 Oct 2026.

All about pricing
PlanPriceWhat it gives you
MutPyFreeNo paid plans or usage limits stated

The facts

Each one read from MutPy's own pages, with the date it was checked.

What it does

Availability
PyPI lists version 0.6.1, released November 17, 2019.checked 9 Oct 2026
Compatibility
The README describes MutPy as supporting Python 3.3+ source code.checked 4 Oct 2026
Development origin
The project says it was developed as part of engineering and master's theses at Warsaw University of Technology's Institute of Computer Science.checked 9 Oct 2026
Installation
The project README gives pip installation and source installation instructions.checked 9 Oct 2026
Integrations
The documented test runner integrations are unittest and experimental pytest; no other integrations are listed.checked 9 Oct 2026
Intended users
PyPI classifies the package for developers and software testing.checked 9 Oct 2026
License
The project is licensed under the Apache License, Version 2.0.checked 9 Oct 2026
Limitations
The README warns that disabling stdout can damage tests that interact with sys.stdout.checked 9 Oct 2026
Mutation controls
Command line options include selecting or disabling operators, sampling a percentage of mutants, and mutating only covered code.checked 9 Oct 2026
Mutation features
It supports higher order mutations and code coverage analysis.checked 9 Oct 2026
Mutation method
It applies mutations at the abstract syntax tree level.checked 9 Oct 2026
Mutation options
It supports higher order mutations and code coverage analysis, including an option to mutate only covered code.checked 4 Oct 2026
Operators
It includes standard mutation operators and a separate set of experimental operators.checked 4 Oct 2026
Purpose
MutPy is a mutation testing tool for Python source code that evaluates the quality of software tests.checked 9 Oct 2026
Python versions
The README describes support for Python 3.3 and later.checked 9 Oct 2026
Release history
PyPI lists version 0.6.1, released November 17, 2019, as the latest release.checked 4 Oct 2026
Reports
MutPy can generate YAML and HTML reports and colorful console output.checked 9 Oct 2026
Support and security
The repository page has an Issues section; it does not state a support service or security certification.checked 4 Oct 2026
Test runners
It supports unittest by default and pytest experimentally.checked 9 Oct 2026
Use case
The README presents MutPy as a tool for developers to find weaknesses in their tests by checking whether tests detect mutated code.checked 4 Oct 2026

Money

Price and license
The project is licensed under Apache License 2.0; the page does not state a price.checked 4 Oct 2026

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