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Contributing

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

Feature requests and feedback

Do you like pytest? Share some love on Twitter or in your blog posts!

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 pytest 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 pytest 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. See also the "good first issue" issues that are friendly to new contributors.

:ref:`Talk <contact>` to developers to find out how you can fix specific bugs. To indicate that you are going to work on a particular issue, add a comment to that effect on the specific issue.

Don't forget to check the issue trackers of your favourite plugins, too!

Implement features

Look through the GitHub issues for enhancements.

:ref:`Talk <contact>` to developers to find out how you can implement specific features.

Write documentation

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

  • More complementary documentation. Have you perhaps found something unclear?
  • Documentation translations. We currently have only English.
  • 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.

Note

Build the documentation locally with the following command:

$ tox -e docs

The built documentation should be available in doc/en/_build/html, where 'en' refers to the documentation language.

Pytest has an API reference which in large part is generated automatically from the docstrings of the documented items. Pytest uses the Sphinx docstring format. For example:

def my_function(arg: ArgType) -> Foo:
    """Do important stuff.

    More detailed info here, in separate paragraphs from the subject line.
    Use proper sentences -- start sentences with capital letters and end
    with periods.

    Can include annotated documentation:

    :param short_arg: An argument which determines stuff.
    :param long_arg:
        A long explanation which spans multiple lines, overflows
        like this.
    :returns: The result.
    :raises ValueError:
        Detailed information when this can happen.

    .. versionadded:: 6.0

    Including types into the annotations above is not necessary when
    type-hinting is being used (as in this example).
    """

Submitting Plugins to pytest-dev

Development of the pytest core, support code, and some plugins happens in repositories living under the pytest-dev organisations:

All pytest-dev Contributors team members have write access to all contained repositories. Pytest core and plugins are generally developed using pull requests to respective repositories.

The objectives of the pytest-dev organisation are:

  • Having a central location for popular pytest plugins
  • Sharing some of the maintenance responsibility (in case a maintainer no longer wishes to maintain a plugin)

You can submit your plugin by subscribing to the pytest-dev mail list and writing a mail pointing to your existing pytest plugin repository which must have the following:

  • PyPI presence with packaging metadata that contains a pytest- prefixed name, version number, authors, short and long description.
  • a tox configuration for running tests using tox.
  • a README describing how to use the plugin and on which platforms it runs.
  • a LICENSE file containing the licensing information, with matching info in its packaging metadata.
  • an issue tracker for bug reports and enhancement requests.
  • a changelog.

If no contributor strongly objects and two agree, the repository can then be transferred to the pytest-dev organisation.

Here's a rundown of how a repository transfer usually proceeds (using a repository named joedoe/pytest-xyz as example):

  • joedoe transfers repository ownership to pytest-dev administrator calvin.
  • calvin creates pytest-xyz-admin and pytest-xyz-developers teams, inviting joedoe to both as maintainer.
  • calvin transfers repository to pytest-dev and configures team access:
    • pytest-xyz-admin admin access;
    • pytest-xyz-developers write access;

The pytest-dev/Contributors team has write access to all projects, and every project administrator is in it. We recommend that each plugin has at least three people who have the right to release to PyPI.

Repository owners can rest assured that no pytest-dev administrator will ever make releases of your repository or take ownership in any way, except in rare cases where someone becomes unresponsive after months of contact attempts. As stated, the objective is to share maintenance and avoid "plugin-abandon".

Preparing Pull Requests

Short version

  1. Fork the repository.

  2. Fetch tags from upstream if necessary (if you cloned only main git fetch --tags https://github.com/pytest-dev/pytest).

  3. Enable and install pre-commit to ensure style-guides and code checks are followed.

  4. Follow PEP-8 for naming.

  5. Tests are run using tox:

    tox -e linting,py39

    The test environments above are usually enough to cover most cases locally.

  6. Write a changelog entry: changelog/2574.bugfix.rst, use issue id number and one of feature, improvement, bugfix, doc, deprecation, breaking, vendor or trivial for the issue type.

  7. Unless your change is a trivial or a documentation fix (e.g., a typo or reword of a small section) please add yourself to the AUTHORS file, in alphabetical order.

Long version

What is a "pull request"? It informs the project's core developers about the changes you want to review and merge. Pull requests are stored on GitHub servers. Once you send a pull request, we can discuss its potential modifications and even add more commits to it later on. There's an excellent tutorial on how Pull Requests work in the GitHub Help Center.

Here is a simple overview, with pytest-specific bits:

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

  2. Clone your fork locally using git and create a branch:

    $ git clone [email protected]:YOUR_GITHUB_USERNAME/pytest.git
$ cd pytest
$ git fetch --tags https://github.com/pytest-dev/pytest
# now, create your own branch off "main":

    $ git checkout -b your-bugfix-branch-name main

    Given we have "major.minor.micro" version numbers, bug fixes will usually be released in micro releases whereas features will be released in minor releases and incompatible changes in major releases.

    You will need the tags to test locally, so be sure you have the tags from the main repository. If you suspect you don't, set the main repository as upstream and fetch the tags:

    $ git remote add upstream https://github.com/pytest-dev/pytest
$ git fetch upstream --tags

    If you need some help with Git, follow this quick start guide: https://git.wiki.kernel.org/index.php/QuickStart

  3. Install pre-commit and its hook on the pytest repo:

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

    Afterwards pre-commit will run whenever you commit.

    https://pre-commit.com/ is a framework for managing and maintaining multi-language pre-commit hooks to ensure code-style and code formatting is consistent.

  4. Install tox

    Tox is used to run all the tests and will automatically setup virtualenvs to run the tests in. (will implicitly use https://virtualenv.pypa.io/en/latest/):

    $ pip install tox

  5. Run all the tests

    You need to have Python 3.8 or later available in your system. Now running tests is as simple as issuing this command:

    $ tox -e linting,py39

    This command will run tests via the "tox" tool against Python 3.9 and also perform "lint" coding-style checks.

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

    You can pass different options to tox. For example, to run tests on Python 3.9 and pass options to pytest (e.g. enter pdb on failure) to pytest you can do:

    $ tox -e py39 -- --pdb

    Or to only run tests in a particular test module on Python 3.9:

    $ tox -e py39 -- testing/test_config.py

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

  7. If instead of using tox you prefer to run the tests directly, then we suggest to create a virtual environment and use an editable install with the dev extra:

    $ python3 -m venv .venv
$ source .venv/bin/activate  # Linux
$ .venv/Scripts/activate.bat  # Windows
$ pip install -e ".[dev]"

    Afterwards, you can edit the files and run pytest normally:

    $ pytest testing/test_config.py

  8. Create a new changelog entry in changelog. The file should be named <issueid>.<type>.rst, where issueid is the number of the issue related to the change and type is one of feature, improvement, bugfix, doc, deprecation, breaking, vendor or trivial. You may skip creating the changelog entry if the change doesn't affect the documented behaviour of pytest.

  9. Add yourself to AUTHORS file if not there yet, in alphabetical order.

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

    $ git commit -a -m "<commit message>"
$ git push -u

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

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

base-fork: pytest-dev/pytest
base: main

Writing Tests

Writing tests for plugins or for pytest itself is often done using the pytester fixture, as a "black-box" test.

For example, to ensure a simple test passes you can write:

def test_true_assertion(pytester):
    pytester.makepyfile(
        """
        def test_foo():
            assert True
    """
    )
    result = pytester.runpytest()
    result.assert_outcomes(failed=0, passed=1)

Alternatively, it is possible to make checks based on the actual output of the termal using glob-like expressions:

def test_true_assertion(pytester):
    pytester.makepyfile(
        """
        def test_foo():
            assert False
    """
    )
    result = pytester.runpytest()
    result.stdout.fnmatch_lines(["*assert False*", "*1 failed*"])

When choosing a file where to write a new test, take a look at the existing files and see if there's one file which looks like a good fit. For example, a regression test about a bug in the --lf option should go into test_cacheprovider.py, given that this option is implemented in cacheprovider.py. If in doubt, go ahead and open a PR with your best guess and we can discuss this over the code.

Joining the Development Team

Anyone who has successfully seen through a pull request which did not require any extra work from the development team to merge will themselves gain commit access if they so wish (if we forget to ask please send a friendly reminder). This does not mean there is any change in your contribution workflow: everyone goes through the same pull-request-and-review process and no-one merges their own pull requests unless already approved. It does however mean you can participate in the development process more fully since you can merge pull requests from other contributors yourself after having reviewed them.

Merge/squash guidelines

When a PR is approved and ready to be integrated to the main branch, one has the option to merge the commits unchanged, or squash all the commits into a single commit.

Here are some guidelines on how to proceed, based on examples of a single PR commit history:

  1. Miscellaneous commits:

    • Implement X
    • Fix test_a
    • Add myself to AUTHORS
    • fixup! Fix test_a
    • Update tests/test_integration.py
    • Merge origin/main into PR branch
    • Update tests/test_integration.py

    In this case, prefer to use the Squash merge strategy: the commit history is a bit messy (not in a derogatory way, often one just commits changes because they know the changes will eventually be squashed together), so squashing everything into a single commit is best. You must clean up the commit message, making sure it contains useful details.

  2. Separate commits related to the same topic:

    • Implement X
    • Add myself to AUTHORS
    • Update CHANGELOG for X

    In this case, prefer to use the Squash merge strategy: while the commit history is not "messy" as in the example above, the individual commits do not bring much value overall, specially when looking at the changes a few months/years down the line.

  3. Separate commits, each with their own topic (refactorings, renames, etc), but still have a larger topic/purpose.

    • Refactor class X in preparation for feature Y
    • Remove unused method
    • Implement feature Y

    In this case, prefer to use the Merge strategy: each commit is valuable on its own, even if they serve a common topic overall. Looking at the history later, it is useful to have the removal of the unused method separately on its own commit, along with more information (such as how it became unused in the first place).

  4. Separate commits, each with their own topic, but without a larger topic/purpose other than improve the code base (using more modern techniques, improve typing, removing clutter, etc).

    • Improve internal names in X
    • Add type annotations to Y
    • Remove unnecessary dict access
    • Remove unreachable code due to EOL Python

    In this case, prefer to use the Merge strategy: each commit is valuable on its own, and the information on each is valuable in the long term.

As mentioned, those are overall guidelines, not rules cast in stone. This topic was discussed in #12633.

Backport PRs (as those created automatically from a backport label) should always be squashed, as they preserve the original PR author.

Backporting bug fixes for the next patch release

Pytest makes a feature release every few weeks or months. In between, patch releases are made to the previous feature release, containing bug fixes only. The bug fixes usually fix regressions, but may be any change that should reach users before the next feature release.

Suppose for example that the latest release was 1.2.3, and you want to include a bug fix in 1.2.4 (check https://github.com/pytest-dev/pytest/releases for the actual latest release). The procedure for this is:

  1. First, make sure the bug is fixed in the main branch, with a regular pull request, as described above. An exception to this is if the bug fix is not applicable to main anymore.

Automatic method:

Add a backport 1.2.x label to the PR you want to backport. This will create a backport PR against the 1.2.x branch.

Manual method:

  1. git checkout origin/1.2.x -b backport-XXXX # use the main PR number here

  2. Locate the merge commit on the PR, in the merged message, for example:

    nicoddemus merged commit 0f8b462 into pytest-dev:main

  3. git cherry-pick -x -m1 REVISION # use the revision you found above (0f8b462).

  4. Open a PR targeting 1.2.x:

    • Prefix the message with [1.2.x].
    • Delete the PR body, it usually contains a duplicate commit message.

Who does the backporting

As mentioned above, bugs should first be fixed on main (except in rare occasions that a bug only happens in a previous release). So, who should do the backport procedure described above?

  1. If the bug was fixed by a core developer, it is the main responsibility of that core developer to do the backport.
  2. However, often the merge is done by another maintainer, in which case it is nice of them to do the backport procedure if they have the time.
  3. For bugs submitted by non-maintainers, it is expected that a core developer will to do the backport, normally the one that merged the PR on main.
  4. If a non-maintainers notices a bug which is fixed on main but has not been backported (due to maintainers forgetting to apply the needs backport label, or just plain missing it), they are also welcome to open a PR with the backport. The procedure is simple and really helps with the maintenance of the project.

All the above are not rules, but merely some guidelines/suggestions on what we should expect about backports.

Backports should be squashed (rather than merged), as doing so preserves the original PR author correctly.

Handling stale issues/PRs

Stale issues/PRs are those where pytest contributors have asked for questions/changes and the authors didn't get around to answer/implement them yet after a somewhat long time, or the discussion simply died because people seemed to lose interest.

There are many reasons why people don't answer questions or implement requested changes: they might get busy, lose interest, or just forget about it, but the fact is that this is very common in open source software.

The pytest team really appreciates every issue and pull request, but being a high-volume project with many issues and pull requests being submitted daily, we try to reduce the number of stale issues and PRs by regularly closing them. When an issue/pull request is closed in this manner, it is by no means a dismissal of the topic being tackled by the issue/pull request, but it is just a way for us to clear up the queue and make the maintainers' work more manageable. Submitters can always reopen the issue/pull request in their own time later if it makes sense.

When to close

Here are a few general rules the maintainers use deciding when to close issues/PRs because of lack of inactivity:

  • Issues labeled question or needs information: closed after 14 days inactive.
  • Issues labeled proposal: closed after six months inactive.
  • Pull requests: after one month, consider pinging the author, update linked issue, or consider closing. For pull requests which are nearly finished, the team should consider finishing it up and merging it.

The above are not hard rules, but merely guidelines, and can be (and often are!) reviewed on a case-by-case basis.

Closing pull requests

When closing a Pull Request, it needs to be acknowledging the time, effort, and interest demonstrated by the person which submitted it. As mentioned previously, it is not the intent of the team to dismiss a stalled pull request entirely but to merely to clear up our queue, so a message like the one below is warranted when closing a pull request that went stale:

Hi <contributor>,

First of all, we would like to thank you for your time and effort on working on this, the pytest team deeply appreciates it.

We noticed it has been awhile since you have updated this PR, however. pytest is a high activity project, with many issues/PRs being opened daily, so it is hard for us maintainers to track which PRs are ready for merging, for review, or need more attention.

So for those reasons we, think it is best to close the PR for now, but with the only intention to clean up our queue, it is by no means a rejection of your changes. We still encourage you to re-open this PR (it is just a click of a button away) when you are ready to get back to it.

Again we appreciate your time for working on this, and hope you might get back to this at a later time!

<bye>

Closing issues

When a pull request is submitted to fix an issue, add text like closes #XYZW to the PR description and/or commits (where XYZW is the issue number). See the GitHub docs for more information.

When an issue is due to user error (e.g. misunderstanding of a functionality), please politely explain to the user why the issue raised is really a non-issue and ask them to close the issue if they have no further questions. If the original requester is unresponsive, the issue will be handled as described in the section Handling stale issues/PRs above.