Contributions are welcome, and they are greatly appreciated! Every little bit helps, and credit will always be given.

Code of Conduct

The development of unyt happens in the context of the yt community code of conduct. If for any reason you feel that the code of conduct has been violated in the context of unyt development, please send an e-mail to with details describing the incident. All emails sent to this address will be treated with the strictest confidence by an individual who does not normally participate in yt development.

Types of Contributions

You can contribute in many ways:

Report Bugs

Report bugs at

If you are reporting a bug, please include:

  • Your operating system name and version.
  • Any details about your local setup that might be helpful in troubleshooting.
  • Detailed steps to reproduce the bug.

Fix Bugs

Look through the GitHub issues for bugs. Anything tagged with “bug” and “help wanted” is open to whoever wants to implement it.

Implement Features

Look through the GitHub issues for features. Anything tagged with “enhancement” and “help wanted” is open to whoever wants to implement it.

Write Documentation

unyt could always use more documentation, whether as part of the official unyt docs, in docstrings, or even on the web in blog posts, articles, and such.

Submit Feedback

The best way to send feedback is to file an issue at

If you are proposing a feature:

  • Explain in detail how it would work.
  • Keep the scope as narrow as possible, to make it easier to implement.
  • Remember that this is a volunteer-driven project, and that contributions are welcome :)

Get Started!

Ready to contribute? Here’s how to set up unyt for local development.

  1. Fork the unyt repo on GitHub.

  2. Clone your fork locally:

    $ git clone
  3. Install your local copy into a virtualenv. Assuming you have virtualenvwrapper installed, this is how you set up your fork for local development:

    $ mkvirtualenv unyt
    $ cd unyt/
    $ python develop
  4. Create a branch for local development:

    $ git checkout -b name-of-your-bugfix-or-feature

    Now you can make your changes locally.

  5. When you’re done making changes, check that your changes pass flake8, format the code with black, and run the tests, including testing several Python versions with tox:

    $ flake8 unyt
    $ black ./
    $ pytest --doctest-modules --doctest-rst --doctest-plus
    $ tox

    To get flake8, black, pytest, pytest-doctestplus, and tox, just pip install them into your virtualenv.

  6. Commit your changes and push your branch to GitHub:

    $ git add .
    $ git commit -m "Your detailed description of your changes."
    $ git push origin name-of-your-bugfix-or-feature
  7. Submit a pull request through the GitHub website.

Testing unyt

We use the pytest test runner as well as the tox test wrapper to manage running tests on various versions of python. To run the tests on your copy of the unyt repository, simply run pytest in the root of the repository:

$ cd unyt/
$ py.test --doctest-modules --doctest-rst --doctest-plus

You will need to install pytest and pytest-doctestplus from pip to run this command. Some tests depend on h5py, Pint, astropy, black, and flake8 being installed.

If you would like to run the tests on multiple python versions, first ensure that you have multiple python versions visible on your $PATH, then simply execute tox in the root of the unyt repository:

$ cd unyt
$ tox

The tox package itself can be installed using the pip associated with one of the python installations. See the tox.ini file in the root of the repository for more details about our tox setup. Note that you do not need to install anything besides tox and python for this to work, tox will handle setting up the test environment, including installing any necessary dependencies via pip.

Pull Request Guidelines

Before you submit a pull request, check that it meets these guidelines:

  1. The pull request should include tests for functionality that is not already tested. We strive for 100% test coverage and pull requests should not add any new untested code. Use the reports on the pull request to gauge coverage. You can also generate coverage reports locally by running the tox tests.
  2. If the pull request adds functionality the docs should be updated. If your new functionality adds new functions or classes to the public API, please add docstrings. If you modified an existing function or class in the public API, please update the existing docstrings. If you modify private implementation details, please use your judgment on documenting it with comments or docstrings.
  3. The pull request should work for Python 3.5, 3.6, and 3.7. Check in the GitHub interface for your pull request and make sure that the tests pass for all supported Python versions.


A reminder for the maintainers on how to deploy. Make sure all your changes are committed (including an entry in HISTORY.rst and adding any new contributors to AUTHORS.rst). Then run:

$ git tag v1.x.x
$ git push upstream master --tags

Travis will then deploy to PyPI if tests pass.