Development on the latest version of Python is preferred. As of this writing it's 3.9.
You can use any operating system.
-Install all development dependencies using:
+Install development dependencies inside a virtual environment of your choice, for
+example:
```console
-$ pipenv install --dev
-$ pipenv shell
-$ pre-commit install
-```
-
-If you haven't used `pipenv` before but are comfortable with virtualenvs, just run
-`pip install pipenv` in the virtualenv you're already using and invoke the command above
-from the cloned _Black_ repo. It will do the correct thing.
-
-Non pipenv install works too:
-
-```console
-$ pip install -r test_requirements
-$ pip install -e .[d]
+$ python3 -m venv .venv
+$ source .venv/bin/activate
+(.venv)$ pip install -r test_requirements.txt
+(.venv)$ pip install -e .[d]
+(.venv)$ pre-commit install
```
Before submitting pull requests, run lints and tests with the following commands from
```console
# Linting
-$ pre-commit run -a
+(.venv)$ pre-commit run -a
# Unit tests
-$ tox -e py
+(.venv)$ tox -e py
# Optional Fuzz testing
-$ tox -e fuzz
+(.venv)$ tox -e fuzz
# Optional CI run to test your changes on many popular python projects
-$ black-primer [-k -w /tmp/black_test_repos]
+(.venv)$ black-primer [-k -w /tmp/black_test_repos]
```
### News / Changelog Requirement
If a change would affect the advertised code style, please modify the documentation (The
_Black_ code style) to reflect that change. Patches that fix unintended bugs in
-formatting don't need to be mentioned separately though.
+formatting don't need to be mentioned separately though. If the change is implemented
+with the `--preview` flag, please include the change in the future style document
+instead and write the changelog entry under a dedicated "Preview changes" heading.
### Docs Testing
If you make changes to docs, you can test they still build locally too.
```console
-$ pip install -r docs/requirements.txt
-$ pip install [-e] .[d]
-$ sphinx-build -a -b html -W docs/ docs/_build/
+(.venv)$ pip install -r docs/requirements.txt
+(.venv)$ pip install [-e] .[d]
+(.venv)$ sphinx-build -a -b html -W docs/ docs/_build/
```
## black-primer
if we get source code changes. It will error on formatting changes or errors. Please run
before pushing your PR to see if you get the actions you would expect from _Black_ with
your PR. You may need to change
-[primer.json](https://github.com/psf/black/blob/master/src/black_primer/primer.json)
+[primer.json](https://github.com/psf/black/blob/main/src/black_primer/primer.json)
configuration for it to pass.
For more `black-primer` information visit the