Contributing to Photutils
=========================

Reporting Issues
----------------

When opening an issue to report a problem, please try to provide a
minimal code example that reproduces the issue.  Also, please include
details of the operating system and the Python, Numpy, Astropy, and
Photutils versions you are using.

Contributing code
-----------------

So you're interested in contributing code to Photutils? Excellent!

Most contributions to Photutils are done via pull requests from GitHub
users' forks of the `Photutils repository
<https://github.com/astropy/photutils>`_. If you're new to this style
of development, you'll want to read over the `Astropy development
workflow
<https://docs.astropy.org/en/latest/development/workflow/development_workflow.html>`_.

Once you open a pull request (which should be opened against the
``master`` branch, not against any other branch), please make sure
that you include the following:

- **Code**: the code you are adding, which should follow as much as
  possible the `Astropy coding guidelines <https://docs.astropy.org/en/latest/development/codeguide.html>`_.

- **Tests**: these are either tests to ensure code that previously
  failed now works (regression tests) or tests that cover as much as
  possible of the new functionality to make sure it doesn't break in
  the future.  The tests are also used to ensure consistent results on
  all platforms, since we run these tests on many
  platforms/configurations. For more information about how to write
  tests, see the `Astropy testing guidelines
  <https://docs.astropy.org/en/latest/development/testguide.html>`_.

- **Documentation**: if you are adding new functionality, be sure to
  include a description in the main documentation (in ``docs/``). For
  more information, please see the detailed `Astropy documentation
  guidelines <https://docs.astropy.org/en/latest/development/docguide.html>`_.

- **Changelog entry**: if you are fixing a bug or adding new
  functionality, you should add an entry to the ``CHANGES.rst`` file
  that includes the PR number and if possible the issue number (if you
  are opening a pull request you may not know this yet, but you can
  add it once the pull request is open). If you're not sure where to
  put the changelog entry, wait until a maintainer has reviewed your
  PR and assigned it to a milestone.

  You do not need to include a changelog entry for fixes to bugs
  introduced in the developer version and therefore are not present in
  the stable releases.  In general, you do not need to include a
  changelog entry for minor documentation or test updates.  Only
  user-visible changes (new features/API changes, fixed issues) need
  to be mentioned.  If in doubt, ask the core maintainer reviewing
  your changes.

Other Tips
----------

- To prevent the automated tests from running you can add ``[ci
  skip]`` to your commit message. This is useful if your PR is a work
  in progress and you are not yet ready for the tests to run.  For
  example:

      $ git commit -m "WIP widget [ci skip]"

  - If you already made the commit without including this string, you can edit
    your existing commit message by running:

        $ git commit --amend

- To skip only the testing on Travis CI use ``[skip travis]``.

- If your commit makes substantial changes to the documentation, but
  no code changes, then you can use ``[docs only]``, that will skip all
  but the documentation building jobs on Travis.

- When contributing trivial documentation fixes (i.e. fixes to typos,
  spelling, grammar) that do not contain any special markup and are
  not associated with code changes, please include the string ``[docs
  only]`` in your commit message.

      $ git commit -m "Fixed typo [docs only]"


Checklist for Contributed Code
------------------------------

A pull request for a new feature will be reviewed to see if it meets the
following requirements.  For any pull request, a Photutils maintainer can
help to make sure that the pull request meets the requirements for inclusion
in the package.

**Scientific Quality**
(when applicable)

* Is the submission relevant to this package?
* Are references included to the original source for the algorithm?
* Does the code perform as expected?
* Has the code been tested against previously existing implementations?

**Code Quality**

* Are the `Astropy coding guidelines <https://docs.astropy.org/en/latest/development/codeguide.html>`_ followed?
* Are there dependencies other than the Astropy core, the Python
  Standard Library, and NumPy?

  - Is the package importable even if the C-extensions are not built?
  - Are additional dependencies handled appropriately?
  - Do functions and classes that require additional dependencies raise
    an `ImportError` if they are not present?

**Testing**

* Are the `Astropy testing guidelines <https://docs.astropy.org/en/latest/development/testguide.html>`_ followed?
* Are the inputs to the functions and classes sufficiently tested?
* Are there tests for any exceptions raised?
* Are there tests for the expected performance?
* Are the sources for the tests documented?
* Are the tests that require an `optional dependency <https://docs.astropy.org/en/latest/development/testguide.html#tests-requiring-optional-dependencies>`_ marked as such?
* Does "``python setup.py test``" run without failures?

**Documentation**

* Are the `Astropy documentation guidelines <https://docs.astropy.org/en/latest/development/docguide.html>`_ followed?
* Is there a `docstring <https://docs.astropy.org/en/latest/development/docrules.html>`_ in the functions and classes describing:

  - What the code does?
  - The format of the inputs of the function or class?
  - The format of the outputs of the function or class?
  - References to the original algorithms?
  - Any exceptions which are raised?
  - An example of running the code?

* Is there any information needed to be added to the docs to describe the function or class?
* Does the documentation build without errors or warnings?

**License**

* Is the photutils license included at the top of the file?
* Are there any conflicts with this code and existing codes?

**Photutils requirements**

* Do all the Travis CI, AppVeyor, and CircleCI tests pass?
* If applicable, has an entry been added into the changelog?
* Can you checkout the pull request and repeat the examples and tests?
