beets/CONTRIBUTING.rst

Contributing
============

.. contents::
    :depth: 3

Thank you!
----------

First off, thank you for considering contributing to beets! It’s people like you
that make beets continue to succeed.

These guidelines describe how you can help most effectively. By following these
guidelines, you can make life easier for the development team as it indicates
you respect the maintainers’ time; in return, the maintainers will reciprocate
by helping to address your issue, review changes, and finalize pull requests.

Types of Contributions
----------------------

We love to get contributions from our community—you! There are many ways to
contribute, whether you’re a programmer or not.

The first thing to do, regardless of how you'd like to contribute to the
project, is to check out our :doc:`Code of Conduct <code_of_conduct>` and to
keep that in mind while interacting with other contributors and users.

Non-Programming
~~~~~~~~~~~~~~~

- Promote beets! Help get the word out by telling your friends, writing a blog
  post, or discussing it on a forum you frequent.
- Improve the documentation_. It’s incredibly easy to contribute here: just find
  a page you want to modify and hit the “Edit on GitHub” button in the
  upper-right. You can automatically send us a pull request for your changes.
- GUI design. For the time being, beets is a command-line-only affair. But
  that’s mostly because we don’t have any great ideas for what a good GUI should
  look like. If you have those great ideas, please get in touch.
- Benchmarks. We’d like to have a consistent way of measuring speed improvements
  in beets’ tagger and other functionality as well as a way of comparing beets’
  performance to other tools. You can help by compiling a library of
  freely-licensed music files (preferably with incorrect metadata) for testing
  and measurement.
- Think you have a nice config or cool use-case for beets? We’d love to hear
  about it! Submit a post to our `discussion board
  <https://github.com/beetbox/beets/discussions/categories/show-and-tell>`__
  under the “Show and Tell” category for a chance to get featured in `the docs
  <https://beets.readthedocs.io/en/stable/guides/advanced.html>`__.
- Consider helping out fellow users by by `responding to support requests
  <https://github.com/beetbox/beets/discussions/categories/q-a>`__ .

Programming
~~~~~~~~~~~

- As a programmer (even if you’re just a beginner!), you have a ton of
  opportunities to get your feet wet with beets.
- For developing plugins, or hacking away at beets, there’s some good
  information in the `“For Developers” section of the docs
  <https://beets.readthedocs.io/en/stable/dev/>`__.

.. _development-tools:

Development Tools
+++++++++++++++++

In order to develop beets, you will need a few tools installed:

- poetry_ for packaging, virtual environment and dependency management
- poethepoet_ to run tasks, such as linting, formatting, testing

Python community recommends using pipx_ to install stand-alone command-line
applications such as above. pipx_ installs each application in an isolated
virtual environment, where its dependencies will not interfere with your system
and other CLI tools.

If you do not have pipx_ installed in your system, follow `pipx installation
instructions <https://pipx.pypa.io/stable/installation/>`__ or

.. code-block:: sh

    $ python3 -m pip install --user pipx

Install poetry_ and poethepoet_ using pipx_:

::

    $ pipx install poetry poethepoet

.. admonition:: Check ``tool.pipx-install`` section in ``pyproject.toml`` to see supported versions

    .. code-block:: toml

        [tool.pipx-install]
        poethepoet = ">=0.26"
        poetry = "<2"

.. _getting-the-source:

Getting the Source
++++++++++++++++++

The easiest way to get started with the latest beets source is to clone the
repository and install ``beets`` in a local virtual environment using poetry_.
This can be done with:

.. code-block:: bash

    $ git clone https://github.com/beetbox/beets.git
    $ cd beets
    $ poetry install

This will install ``beets`` and all development dependencies into its own
virtual environment in your ``$POETRY_CACHE_DIR``. See ``poetry install --help``
for installation options, including installing ``extra`` dependencies for
plugins.

In order to run something within this virtual environment, start the command
with ``poetry run`` to them, for example ``poetry run pytest``.

On the other hand, it may get tedious to type ``poetry run`` before every
command. Instead, you can activate the virtual environment in your shell with:

::

    $ poetry shell

You should see ``(beets-py3.9)`` prefix in your shell prompt. Now you can run
commands directly, for example:

::

    $ (beets-py3.9) pytest

Additionally, poethepoet_ task runner assists us with the most common
operations. Formatting, linting, testing are defined as ``poe`` tasks in
pyproject.toml_. Run:

::

    $ poe

to see all available tasks. They can be used like this, for example

.. code-block:: sh

    $ poe lint                  # check code style
    $ poe format                # fix formatting issues
    $ poe test                  # run tests
    # ... fix failing tests
    $ poe test --lf             # re-run failing tests (note the additional pytest option)
    $ poe check-types --pretty  # check types with an extra option for mypy

Code Contribution Ideas
+++++++++++++++++++++++

- We maintain a set of `issues marked as “good first issue”
  <https://github.com/beetbox/beets/labels/good%20first%20issue>`__. These are
  issues that would serve as a good introduction to the codebase. Claim one and
  start exploring!
- Like testing? Our `test coverage <https://codecov.io/github/beetbox/beets>`__
  is somewhat low. You can help out by finding low-coverage modules or checking
  out other `testing-related issues
  <https://github.com/beetbox/beets/labels/testing>`__.
- There are several ways to improve the tests in general (see :ref:`testing` and
  some places to think about performance optimization (see `Optimization
  <https://github.com/beetbox/beets/wiki/Optimization>`__).
- Not all of our code is up to our coding conventions. In particular, the
  `library API documentation
  <https://beets.readthedocs.io/en/stable/dev/library.html>`__ are currently
  quite sparse. You can help by adding to the docstrings in the code and to the
  documentation pages themselves. beets follows `PEP-257
  <https://www.python.org/dev/peps/pep-0257/>`__ for docstrings and in some
  places, we also sometimes use `ReST autodoc syntax for Sphinx
  <https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html>`__ to,
  for example, refer to a class name.

Your First Contribution
-----------------------

If this is your first time contributing to an open source project, welcome! If
you are confused at all about how to contribute or what to contribute, take a
look at `this great tutorial <http://makeapullrequest.com/>`__, or stop by our
`discussion board`_ if you have any questions.

We maintain a list of issues we reserved for those new to open source labeled
`first timers only`_. Since the goal of these issues is to get users comfortable
with contributing to an open source project, please do not hesitate to ask any
questions.

.. _first timers only: https://github.com/beetbox/beets/issues?q=is%3Aopen+is%3Aissue+label%3A%22first+timers+only%22

How to Submit Your Work
-----------------------

Do you have a great bug fix, new feature, or documentation expansion you’d like
to contribute? Follow these steps to create a GitHub pull request and your code
will ship in no time.

1. Fork the beets repository and clone it (see above) to create a workspace.
2. Install pre-commit, following the instructions `here
   <https://pre-commit.com/>`_.
3. Make your changes.
4. Add tests. If you’ve fixed a bug, write a test to ensure that you’ve actually
   fixed it. If there’s a new feature or plugin, please contribute tests that
   show that your code does what it says.
5. Add documentation. If you’ve added a new command flag, for example, find the
   appropriate page under ``docs/`` where it needs to be listed.
6. Add a changelog entry to ``docs/changelog.rst`` near the top of the document.
7. Run the tests and style checker, see :ref:`testing`.
8. Push to your fork and open a pull request! We’ll be in touch shortly.
9. If you add commits to a pull request, please add a comment or re-request a
   review after you push them since GitHub doesn’t automatically notify us when
   commits are added.

Remember, code contributions have four parts: the code, the tests, the
documentation, and the changelog entry. Thank you for contributing!

.. admonition:: Ownership

    If you are the owner of a plugin, please consider reviewing pull requests
    that affect your plugin. If you are not the owner of a plugin, please
    consider becoming one! You can do so by adding an entry to
    ``.github/CODEOWNERS``. This way, you will automatically receive a review
    request for pull requests that adjust the code that you own. If you have any
    questions, please ask on our `discussion board`_.

The Code
--------

The documentation has a section on the `library API
<https://beets.readthedocs.io/en/stable/dev/library.html>`__ that serves as an
introduction to beets’ design.

Coding Conventions
------------------

General
~~~~~~~

There are a few coding conventions we use in beets:

- Whenever you access the library database, do so through the provided Library
  methods or via a Transaction object. Never call ``lib.conn.*`` directly. For
  example, do this:

  .. code-block:: python

      with g.lib.transaction() as tx:
          rows = tx.query("SELECT DISTINCT {field} FROM {model._table} ORDER BY {sort_field}")

  To fetch Item objects from the database, use lib.items(…) and supply a query
  as an argument. Resist the urge to write raw SQL for your query. If you must
  use lower-level queries into the database, do this, for example:

  .. code-block:: python

      with lib.transaction() as tx:
          rows = tx.query("SELECT path FROM items WHERE album_id = ?", (album_id,))

  Transaction objects help control concurrent access to the database and assist
  in debugging conflicting accesses.

- f-strings should be used instead of the ``%`` operator and ``str.format()``
  calls.
- Never ``print`` informational messages; use the `logging
  <http://docs.python.org/library/logging.html>`__ module instead. In
  particular, we have our own logging shim, so you’ll see ``from beets import
  logging`` in most files.

  - The loggers use `str.format
    <http://docs.python.org/library/stdtypes.html#str.format>`__-style logging
    instead of ``%``-style, so you can type ``log.debug("{}", obj)`` to do your
    formatting.

- Exception handlers must use ``except A as B:`` instead of ``except A, B:``.

Style
~~~~~

We use `ruff <https://docs.astral.sh/ruff/>`__ to format and lint the codebase.

Run ``poe check-format`` and ``poe lint`` to check your code for style and
linting errors. Running ``poe format`` will automatically format your code
according to the specifications required by the project.

Similarly, run ``poe format-docs`` and ``poe lint-docs`` to ensure consistent
documentation formatting and check for any issues.

Editor Settings
~~~~~~~~~~~~~~~

Personally, I work on beets with vim_. Here are some ``.vimrc`` lines that might
help with PEP 8-compliant Python coding:

::

    filetype indent on
    autocmd FileType python setlocal shiftwidth=4 tabstop=4 softtabstop=4 expandtab shiftround autoindent

Consider installing `this alternative Python indentation plugin
<https://github.com/mitsuhiko/vim-python-combined>`__. I also like `neomake
<https://github.com/neomake/neomake>`__ with its flake8 checker.

.. _testing:

Testing
-------

Running the Tests
~~~~~~~~~~~~~~~~~

Use ``poe`` to run tests:

::

    $ poe test [pytest options]

You can disable a hand-selected set of "slow" tests by setting the environment
variable ``SKIP_SLOW_TESTS``, for example:

::

    $ SKIP_SLOW_TESTS=1 poe test

Coverage
++++++++

The ``test`` command does not include coverage as it slows down testing. In
order to measure it, use the ``test-with-coverage`` task

    $ poe test-with-coverage [pytest options]

You are welcome to explore coverage by opening the HTML report in
``.reports/html/index.html``.

Note that for each covered line the report shows **which tests cover it**
(expand the list on the right-hand side of the affected line).

You can find project coverage status on Codecov_.

Red Flags
+++++++++

The pytest-random_ plugin makes it easy to randomize the order of tests. ``poe
test --random`` will occasionally turn up failing tests that reveal ordering
dependencies—which are bad news!

Test Dependencies
+++++++++++++++++

The tests have a few more dependencies than beets itself. (The additional
dependencies consist of testing utilities and dependencies of non-default
plugins exercised by the test suite.) The dependencies are listed under the
``tool.poetry.group.test.dependencies`` section in pyproject.toml_.

Writing Tests
~~~~~~~~~~~~~

Writing tests is done by adding or modifying files in folder test_. Take a look
at `https://github.com/beetbox/beets/blob/master/test/test_template.py#L224`_ to
get a basic view on how tests are written. Since we are currently migrating the
tests from unittest_ to pytest_, new tests should be written using pytest_.
Contributions migrating existing tests are welcome!

External API requests under test should be mocked with requests-mock_, However,
we still want to know whether external APIs are up and that they return expected
responses, therefore we test them weekly with our `integration test`_ suite.

In order to add such a test, mark your test with the ``integration_test`` marker

.. code-block:: python

    @pytest.mark.integration_test
    def test_external_api_call(): ...

This way, the test will be run only in the integration test suite.

.. _codecov: https://codecov.io/github/beetbox/beets

.. _discussion board: https://github.com/beetbox/beets/discussions

.. _documentation: https://beets.readthedocs.io/en/stable/

.. _https://github.com/beetbox/beets/blob/master/test/test_template.py#l224: https://github.com/beetbox/beets/blob/master/test/test_template.py#L224

.. _integration test: https://github.com/beetbox/beets/actions?query=workflow%3A%22integration+tests%22

.. _pipx: https://pipx.pypa.io/stable

.. _poethepoet: https://poethepoet.natn.io/index.html

.. _poetry: https://python-poetry.org/docs/

.. _pyproject.toml: https://github.com/beetbox/beets/tree/master/pyproject.toml

.. _pytest: https://docs.pytest.org/en/stable/

.. _pytest-random: https://github.com/klrmn/pytest-random

.. _requests-mock: https://requests-mock.readthedocs.io/en/latest/response.html

.. _test: https://github.com/beetbox/beets/tree/master/test

.. _unittest: https://docs.python.org/3/library/unittest.html

.. _vim: https://www.vim.org/