.. _contributing:

************
Contributing
************

If you are thinking about making Mopidy better, or you just want to hack on it,
that’s great. Here are some tips to get you started.


Getting started
===============

#. Make sure you have a `GitHub account <https://github.com/signup/free>`_.

#. If a ticket does not already exist `submit a ticket
   <https://github.com/mopidy/mopidy/issues/new>`_ for your issue.
   Make sure to clearly describe the issue, and if it is a bug: include steps
   to reproduce.

#. Fork the repository on GitHub.


Making changes
==============

#. Clone your fork on GitHub to your computer.

#. Consider making a Python `virtualenv <http://www.virtualenv.org/>`_ for
   Mopidy development to wall of Mopidy and it's dependencies from the rest of
   your system. If you do so, create the virtualenv with the
   ``--system-site-packages`` flag so that Mopidy can use globally installed
   dependencies like GStreamer. If you don't use a virtualenv, you may need to
   run the following ``pip`` and ``python setup.py`` commands with ``sudo`` to
   install stuff globally on your computer.

#. Install dependencies as described in the :ref:`installation` section.

#. Install additional development dependencies::

       pip install -r dev-requirements.txt

#. Checkout a new branch (usually based on ``develop``) and name it accordingly
   to what you intend to do.

   - Features get the prefix ``feature/``

   - Bug fixes get the prefix ``fix/``

   - Improvements to the documentation get the prefix ``docs/``


.. _run-from-git:

Running Mopidy from Git
=======================

If you want to hack on Mopidy, you should run Mopidy directly from the Git
repo.

#. Go to the Git repo root::

       cd mopidy/

#. To get a ``mopidy`` executable and register all bundled extensions with
   setuptools, run::

      python setup.py develop

   It still works to run ``python mopidy`` directly on the ``mopidy`` Python
   package directory, but if you have never run ``python setup.py develop`` the
   extensions bundled with Mopidy isn't registered with setuptools, so Mopidy
   will start without any frontends or backends, making it quite useless.

#. Now you can run the Mopidy command, and it will run using the code
   in the Git repo::

      mopidy

   If you do any changes to the code, you'll just need to restart ``mopidy``
   to see the changes take effect.


Testing
=======

Mopidy has quite good test coverage, and we would like all new code going into
Mopidy to come with tests.

#. To run all tests, go to the project directory and run::

       py.test

   To run tests with test coverage statistics::

       py.test --cov=mopidy --cov-report=term-missing

   Test coverage statistics can also be viewed online at
   `coveralls.io <https://coveralls.io/r/mopidy/mopidy>`_.

#. Always check the code for errors and style issues using flake8::

       flake8

   If successful, the command will not print anything at all. Ignore the rare
   cases you need to ignore a check use `# noqa: <code>` so we can lookup what
   you are ignoring.

#. Finally, there is the ultimate but a bit slower command. To run both tests,
   docs build, and flake8 linting, run::

       tox

   This will run exactly the same tests as `Travis CI
   <https://travis-ci.org/mopidy/mopidy>`_ runs for all our branches and pull
   requests. If this command turns green, you can be quite confident that your
   pull request will get the green flag from Travis as well, which is a
   requirement for it to be merged.


Submitting changes
==================

- One branch per feature or fix. Keep branches small and on topic.

- Follow the :ref:`code style <codestyle>`, especially make sure ``flake8``
  does not complain about anything.

- Write good commit messages. Here's three blog posts on how to do it right:

  - `Writing Git commit messages
    <http://365git.tumblr.com/post/3308646748/writing-git-commit-messages>`_

  - `A Note About Git Commit Messages
    <http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html>`_

  - `On commit messages
    <http://who-t.blogspot.ch/2009/12/on-commit-messages.html>`_

- Send a pull request to the ``develop`` branch. See the `GitHub pull request
  docs <https://help.github.com/articles/using-pull-requests>`_ for help.


Additional resources
====================

- IRC channel: ``#mopidy`` at `irc.freenode.net <http://freenode.net/>`_

- `Issue tracker <https://github.com/mopidy/mopidy/issues>`_

- `Mailing List <https://groups.google.com/forum/?fromgroups=#!forum/mopidy>`_

- `GitHub documentation <https://help.github.com/>`_
