mutatest: Python mutation testing

Are you confident in your tests? Try out mutatest and see if your tests will detect small modifications (mutations) in the code. Surviving mutations represent subtle changes that are undetectable by your tests. These mutants are potential modifications in source code that continuous integration checks would miss.

Features

• Simple command line tool with multiple configuration options.
• Built on Python's Abstract Syntax Tree (AST) grammar to ensure mutants are valid.
• No source code modification, only the __pycache__ is changed.
• Uses coverage to create only meaningful mutants.
• Built for efficiency with multiple running modes and random sampling of mutation targets.
• Capable of running parallel mutation trials with multiprocessing on Python 3.8.
• Flexible enough to run on a whole package or a single file.
• Includes an API for custom mutation controls.
• Tested on Linux, Windows, and MacOS with Azure pipelines.
• Full strict static type annotations throughout the source code and the API.

Install

Install from PyPI:

$ pip install mutatest

Install from conda-forge:

$ conda install -c conda-forge mutatest

Example Output

This is an output example running mutation trials against the API Tutorial example folder example folder.

$ mutatest -s example/ -t "pytest" -r 314

Running clean trial
2 mutation targets found in example/a.py AST.
1 mutation targets found in example/b.py AST.
Setting random.seed to: 314
Total sample space size: 2
10 exceeds sample space, using full sample: 2.

Starting individual mutation trials!
Current target location: a.py, LocIndex(ast_class='BinOp', lineno=6, col_offset=11, op_type=<class '_ast.Add'>)
Detected mutation at example/a.py: (6, 11)
Detected mutation at example/a.py: (6, 11)
Surviving mutation at example/a.py: (6, 11)
Break on survival: stopping further mutations at location.

Current target location: b.py, LocIndex(ast_class='CompareIs', lineno=6, col_offset=11, op_type=<class '_ast.Is'>)
Detected mutation at example/b.py: (6, 11)
Running clean trial

Mutatest diagnostic summary
===========================
 - Source location: /home/user/Github/mutatest/docs/api_tutorial/example
 - Test commands: ['pytest']
 - Mode: s
 - Excluded files: []
 - N locations input: 10
 - Random seed: 314

Random sample details
---------------------
 - Total locations mutated: 2
 - Total locations identified: 2
 - Location sample coverage: 100.00 %


Running time details
--------------------
 - Clean trial 1 run time: 0:00:00.348999
 - Clean trial 2 run time: 0:00:00.350213
 - Mutation trials total run time: 0:00:01.389095

Trial Summary Report:

Overall mutation trial summary
==============================
 - DETECTED: 3
 - SURVIVED: 1
 - TOTAL RUNS: 4
 - RUN DATETIME: 2019-10-17 16:57:08.645355

Detected mutations:

DETECTED
--------
 - example/a.py: (l: 6, c: 11) - mutation from <class '_ast.Add'> to <class '_ast.Sub'>
 - example/a.py: (l: 6, c: 11) - mutation from <class '_ast.Add'> to <class '_ast.Mod'>
 - example/b.py: (l: 6, c: 11) - mutation from <class '_ast.Is'> to <class '_ast.IsNot'>

Surviving mutations:

SURVIVED
--------
 - example/a.py: (l: 6, c: 11) - mutation from <class '_ast.Add'> to <class '_ast.Mult'>

Documentation

For full documentation, including installation, CLI references, API references, and tutorials, please see https://mutatest.readthedocs.io/en/latest/. The project is hosted on PyPI at https://pypi.org/project/mutatest/.

Bugs/Requests

Please use the GitHub issue tracker to submit bugs or request features. See the Contributing Guidelines if you are interested in submitting code in the form of pull requests.

ChangeLog

Consult the Changelog page for fixes and enhancements of each version.

License

Copyright Evan Kepner 2018-2020.

Distributed under the terms of the MIT license, mutatest is free and open source software.