MutPy
What it is
MutPy is an open-source mutation testing tool for Python source code. It helps developers examine whether tests detect code changes by applying mutations at the abstract syntax tree level and running the tests. The default test runner is unittest; pytest support is experimental. MutPy can create YAML and HTML reports, analyze code coverage and restrict mutations to covered code. It also supports higher order mutations, and command-line options let users select or disable operators, sample a percentage of mutants and configure covered-code mutations. The tool includes standard and experimental mutation operators. Its README describes support for Python 3.3 and later. Installation is available through pip from PyPI or from repository source. The project is licensed under Apache License 2.0, and the plan is listed as free. PyPI lists version 0.6.1, released November 17, 2019, as the latest release. The README cautions that disabling stdout can damage tests that interact with sys.stdout. The repository has an Issues section, but no support service or security certification is stated.
For and against
For
- Applies mutations at the abstract syntax tree level.
- Generates YAML and HTML reports.
- Can restrict mutations to code covered by tests.
- Offers operator selection and mutant sampling controls.
- Licensed under Apache License 2.0.
Against
- pytest support is experimental.
- The latest listed release is version 0.6.1 from November 17, 2019.
- Disabling stdout can damage tests that use sys.stdout.
The verdict
MutPy provides configurable mutation testing and reporting for Python projects. Its experimental pytest runner and the README’s stdout warning are worth noting before use.
Who it suits
MutPy suits developers who want to assess Python tests with mutation testing. It may fit projects using unittest, or pytest if experimental runner support is acceptable.
Plans and prices
MutPy
No paid plans or usage limits stated
Read 9 Oct 2026 · github.com
On the record
- Availability
- PyPI lists version 0.6.1, released November 17, 2019.pypi.org · read 9 Oct 2026
- Compatibility
- The README describes MutPy as supporting Python 3.3+ source code.github.com · read 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.github.com · read 9 Oct 2026
- Installation
- The project README gives pip installation and source installation instructions.github.com · read 9 Oct 2026
- Integrations
- The documented test runner integrations are unittest and experimental pytest; no other integrations are listed.github.com · read 9 Oct 2026
- Intended users
- PyPI classifies the package for developers and software testing.pypi.org · read 9 Oct 2026
- License
- The project is licensed under the Apache License, Version 2.0.github.com · read 9 Oct 2026
- Limitations
- The README warns that disabling stdout can damage tests that interact with sys.stdout.github.com · read 9 Oct 2026
- Mutation controls
- Command line options include selecting or disabling operators, sampling a percentage of mutants, and mutating only covered code.github.com · read 9 Oct 2026
- Mutation features
- It supports higher order mutations and code coverage analysis.github.com · read 9 Oct 2026
- Mutation method
- It applies mutations at the abstract syntax tree level.github.com · read 9 Oct 2026
- Mutation options
- It supports higher order mutations and code coverage analysis, including an option to mutate only covered code.github.com · read 4 Oct 2026
- Operators
- It includes standard mutation operators and a separate set of experimental operators.github.com · read 4 Oct 2026
- Price and license
- The project is licensed under Apache License 2.0; the page does not state a price.github.com · read 4 Oct 2026
- Purpose
- MutPy is a mutation testing tool for Python source code that evaluates the quality of software tests.github.com · read 9 Oct 2026
- Python versions
- The README describes support for Python 3.3 and later.github.com · read 9 Oct 2026
- Release history
- PyPI lists version 0.6.1, released November 17, 2019, as the latest release.pypi.org · read 4 Oct 2026
- Reports
- MutPy can generate YAML and HTML reports and colorful console output.github.com · read 9 Oct 2026
