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.. intro-start

:title:A lint framework that writes better Python code for you.

Fixit is a lint framework that complements Flake8 <https://github.com/PyCQA/flake8>. It’s based on LibCST <https://github.com/Instagram/LibCST/> which makes it possible to provide auto-fixes. Lint rules are made easy to build through pattern matching, a test toolkit, and utility helpers (e.g. scope analysis) for non-trivial boilerplate. It is optimized for efficiency, easy to customize and comes with many builtin lint rules.

.. intro-end

Getting Started

To install Fixit::

pip install fixit

Fixit provides CLI commands. To run built-in Fixit rules on existing code to get code quality suggestions::

python -m fixit.cli.run_rules

To apply autofix on existing code::

python -m fixit.cli.apply_fix

You can learn more about how to configure Fixit <https://fixit.readthedocs.io/en/latest/getting_started.html#Configuration-File>, build a lint rule <https://fixit.readthedocs.io/en/latest/build_a_lint_rule.html>, test a lint rule <https://fixit.readthedocs.io/en/latest/test_a_lint_rule.html>_ from our tutorials. Try it out with our notebook examples <https://fixit.readthedocs.io/en/latest/getting_started.html>_.

Further Reading

• Static Analysis at Scale: An Instagram Story. <https://instagram-engineering.com/static-analysis-at-scale-an-instagram-story-8f498ab71a0c>_

Development

Start by setting up and activating a virtualenv:

.. code-block:: shell

git clone [email protected]:Instagram/Fixit.git fixit
cd fixit
python3 -m venv ../fixit-env/  # just an example, put this wherever you want
source ../fixit-env/bin/activate
pip install --upgrade pip  # optional, if you have an old system version of pip
pip install -r requirements.txt -r requirements-dev.txt
# If you're done with the virtualenv, you can leave it by running:
deactivate

We use isort <https://isort.readthedocs.io/en/stable/>_ and black <https://black.readthedocs.io/en/stable/>_ to format code. To format changes to be conformant, run the following in the root:

.. code-block:: shell

tox -e autofix

To run all tests, you'll need to install tox <https://tox.readthedocs.io/en/latest/>_ and do the following in the root: (use py37, py38 to choose from Python version 3.7 or 3.8)::

tox -e py38

You can also run individual unit tests by specifying a module like this::

tox -e py38 -- fixit.common.tests.test_report

To run all test cases of a specific rule (e.g. NoInheritFromObjectRule)::

tox -e py38 -- fixit.tests.NoInheritFromObjectRule

See the unittest documentation <https://docs.python.org/3/library/unittest.html>_ for more examples of how to run tests.

We use Pyre <https://github.com/facebook/pyre-check>_ for type-checking. To verify types for the library, do the following in the root::

pyre --preserve-pythonpath check

To generate documentation, do the following in the root:

.. code-block:: shell

tox -e docs

License

Fixit is MIT licensed <LICENSE>_, as found in the LICENSE file.

.. fb-docs-start

Privacy Policy and Terms of Use

• Privacy Policy <https://opensource.facebook.com/legal/privacy>_
• Terms of Use <https://opensource.facebook.com/legal/terms>_

.. fb-docs-end