Contribution Guide

Interested in helping build Esmlab? Have code from your research that you believe others will find useful? Have a few minutes to tackle an issue?

Contributions are highly welcomed and appreciated. Every little help counts, so do not hesitate!

The following sections cover some general guidelines regarding development in esmlab for maintainers and contributors. Nothing here is set in stone and can’t be changed. Feel free to suggest improvements or changes in the workflow.

Feature requests and feedback

We’d also like to hear about your propositions and suggestions. Feel free to submit them as issues and:

  • Explain in detail how they should work.

  • Keep the scope as narrow as possible. This will make it easier to implement.

Report bugs

Report bugs for esmlab in the issue tracker.

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, specifically the Python interpreter version, installed libraries, and esmlab version.

  • Detailed steps to reproduce the bug.

If you can write a demonstration test that currently fails but should pass (xfail), that is a very useful commit to make as well, even if you cannot fix the bug itself.

Fix bugs

Look through the GitHub issues for bugs.

Talk to developers to find out how you can fix specific bugs.

Write documentation

Esmlab could always use more documentation. What exactly is needed?

  • More complementary documentation. Have you perhaps found something unclear?

  • Docstrings. There can never be too many of them.

  • Blog posts, articles and such – they’re all very appreciated.

You can also edit documentation files directly in the GitHub web interface, without using a local copy. This can be convenient for small fixes.


Build the documentation locally with the following command:

$ conda env update -f ci/environment-dev-3.7.yml
$ cd docs
$ make html

The built documentation should be available in the docs/_build/.

Preparing Pull Requests

  1. Fork the esmlab GitHub repository. It’s fine to use esmlab as your fork repository name because it will live under your user.

  2. Clone your fork locally using git, connect your repository to the upstream (main project), and create a branch:

    $ git clone
    $ cd esmlab
    $ git remote add upstream
    # now, to fix a bug or add feature create your own branch off "master":
    $ git checkout -b your-bugfix-feature-branch-name master

    If you need some help with Git, follow this quick start guide:

  3. Install dependencies into a new conda environment:

    $ conda env update -f ci/environment-dev-3.7.yml
    $ conda activate esmlab-dev
  4. Make an editable install of esmlab by running:

    $ pip install -e .
  5. Install pre-commit and its hook on the esmlab repo:

    $ pip install --user pre-commit
    $ pre-commit install

    Afterwards pre-commit will run whenever you commit. is a framework for managing and maintaining multi-language pre-commit hooks to ensure code-style and code formatting is consistent.

    Now you have an environment called esmlab-dev that you can work in. You’ll need to make sure to activate that environment next time you want to use it after closing the terminal or your system.

  6. Run all the tests

    Now running tests is as simple as issuing this command:

    $ pytest --junitxml=test-reports/junit.xml --cov=./

    This command will run tests via the “pytest” tool against Python 3.7.

  7. Create a new changelog entry in CHANGELOG.rst:

    • The entry should be entered as:

    <description> (:pr:`#<pull request number>`) `<author's names>`_

    where <description> is the description of the PR related to the change and <pull request number> is the pull request number and <author's names> are your first and last names.

    • Add yourself to list of authors at the end of CHANGELOG.rst file if not there yet, in alphabetical order.

  8. You can now edit your local working copy and run the tests again as necessary. Please follow PEP-8 for naming.

    When committing, pre-commit will re-format the files if necessary.

  9. Commit and push once your tests pass and you are happy with your change(s):

    $ git commit -a -m "<commit message>"
    $ git push -u
  10. Finally, submit a pull request through the GitHub website using this data:

    head-fork: YOUR_GITHUB_USERNAME/esmlab
    compare: your-branch-name
    base-fork: NCAR/esmlab
    base: master          # if it's a bugfix or feature