Contribution Guide

Contributions are highly welcomed and appreciated. Every little help counts, so do not hesitate! You can make a high impact on esmtools just by using it and reporting issues.

The following sections cover some general guidelines regarding development in esmtools 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 are eager to hear about your requests for new features and any suggestions about the API, infrastructure, and so on. Feel free to submit these as issues with the label “feature request.”

Please make sure to explain in detail how the feature should work and keep the scope as narrow as possible. This will make it easier to implement in small PRs.

Report bugs

Report bugs for esmtools in the issue tracker with the label “bug”.

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 esmtools version.
  • Detailed steps to reproduce the bug.

If you can write a demonstration test that currently fails but should passm 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

esmtools 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.

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

Our documentation is written in reStructuredText. You can follow our conventions in already written documents. Some helpful guides are located here and here.


Build the documentation locally with the following command:

$ conda env update -f ci/environment-dev-3.6.yml
$ cd docs
$ make html

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

If you need to add new functions to the API, add the functions to api.rst then run sphinx-autogen -o api api.rst from the docs/source directory. You might need to run make clean from the docs/ directory and then make html again to get the links to build properly.

Preparing Pull Requests

  1. Fork the esmtools GitHub repository. It’s fine to use esmtools 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 esmtools
    $ 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 esmtools-dev
  4. Make an editable install of esmtools by running:

    $ pip install -e .
  5. Install pre-commit and its hook on the esmtools 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 esmtools-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.

    You can now edit your local working copy and run/add tests as necessary. Please follow PEP-8 for naming. When committing, pre-commit will modify the files as needed, or will generally be quite clear about what you need to do to pass the commit test.

  6. Break your edits up into reasonably sized commits.

    $ git commit -a -m “<commit message>” $ git push -u

  7. Run all the tests

    Now running tests is as simple as issuing this command:

    $ coverage run --source esmtools -m py.test

    This command will run tests via the “pytest” tool against Python 3.6.

  8. 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.
  1. Add yourself to the contributors <>_ list via docs/source/contributors.rst.

  2. Finally, submit a pull request through the GitHub website using this data


    head-fork: YOUR_GITHUB_USERNAME/esmtools compare: your-branch-name

    base-fork: bradyrx/esmtools base: master

Note that you can create the Pull Request while you’re working on this. The PR will update as you add more commits. esmtools developers and contributors can then review your code and offer suggestions.