===================
 Docutils_ Testing
===================

:Authors: Lea Wiemann <LeWiemann@gmail.com>;
          David Goodger <goodger@python.org>
:Revision: $Revision: 8491 $
:Date: $Date: 2020-02-06 16:10:46 +0100 (Do, 06. Feb 2020) $
:Copyright: This document has been placed in the public domain.

.. _Docutils: http://docutils.sourceforge.net/

.. contents::

When adding new functionality (or fixing bugs), be sure to add test
cases to the test suite.  Practise test-first programming; it's fun,
it's addictive, and it works!

This document describes how to run the Docutils test suite, how the
tests are organized and how to add new tests or modify existing tests.


Running the Test Suite
======================

Before checking in any changes, run the entire Docutils test suite to
be sure that you haven't broken anything.  From a shell::

    cd docutils/test
    ./alltests.py

You should run this with multiple Python versions. You can use ``tox`` for
this purpose. To run tests against all supported versions of Python, run::

    tox

To run against a specific version of Python, use the ``pyNN`` environment.
For example::

    tox -e py37


Python Versions
===============

A docutils release has a commitment to support a minimum version and beyond.
Before a release is cut, tests must pass in all supported Python versions.

Docutils 0.16 supports Python 2.7 and Python 3.5 or later.

Therefore, you should install Python 2.7 as well as 3.5 up to the latest Python
(3.7 at the time of this writing) and always run the tests on all of
them (see `Testing across multiple python versions`_).
In a pinch, the edge cases (2.7, and 3.7) should cover most of it.

Good resources covering the differences between Python versions:

* `What's New in Python 2.7`__
* `What's New in Python 3.5`__
* `What's New in Python 3.6`__
* `What's New in Python 3.7`__
* `PEP 290 - Code Migration and Modernization`__

__ https://docs.python.org/whatsnew/2.7.html
__ https://docs.python.org/3/whatsnew/3.5.html
__ https://docs.python.org/3/whatsnew/3.6.html
__ https://docs.python.org/3/whatsnew/3.7.html
__ http://www.python.org/peps/pep-0290.html

.. _Python Check-in Policies: http://www.python.org/dev/tools.html
.. _sandbox directory:
   http://docutils.svn.sourceforge.net/svnroot/docutils/trunk/sandbox/


Testing across multiple python versions
---------------------------------------

`pyenv`_ can be installed and configured (see `installing pyenv`_) to
test multiple python versions::

    # assuming your system runs 2.7.x
    pyenv install 3.5.7
    pyenv install 3.6.9
    pyenv install 3.7.3
    pyenv global system 3.5.7 3.6.9 3.7.3

    # reset your shims
    rm -rf ~/.pyenv/shims && pyenv rehash

This will give you ``python2.7`` and ``python3.5`` through ``python3.7``.
You will also get ``pip2.7``, ``pip3.5``, etc.

To save time, you can use `tox`_. To install tox, run ``pip install tox``.
Once installed, from shell::

    cd docutils
    tox

.. _tox: https://tox.readthedocs.org/en/latest/
.. _pyenv: https://github.com/yyuu/pyenv
.. _installing pyenv: https://github.com/yyuu/pyenv#installation


Unit Tests
==========

Unit tests test single functions or modules (i.e. whitebox testing).

If you are implementing a new feature, be sure to write a test case
covering its functionality.  It happens very frequently that your
implementation (or even only a part of it) doesn't work with an older
(or even newer) Python version, and the only reliable way to detect
those cases is using tests.

Often, it's easier to write the test first and then implement the
functionality required to make the test pass.


Writing New Tests
-----------------

When writing new tests, it very often helps to see how a similar test
is implemented.  For example, the files in the
``test_parsers/test_rst/`` directory all look very similar.  So when
adding a test, you don't have to reinvent the wheel.

If there is no similar test, you can write a new test from scratch
using Python's ``unittest`` module.  For an example, please have a
look at the following imaginary ``test_square.py``::

    #! /usr/bin/env python

    # $Id: testing.txt 8491 2020-02-06 15:10:46Z milde $
    # Author: Your Name <your_email_address@example.org>
    # Copyright: This module has been placed in the public domain.

    """
    Test module for docutils.square.
    """

    import unittest
    import docutils.square


    class SquareTest(unittest.TestCase):

        def test_square(self):
            self.assertEqual(docutils.square.square(0), 0)
            self.assertEqual(docutils.square.square(5), 25)
            self.assertEqual(docutils.square.square(7), 49)

        def test_square_root(self):
            self.assertEqual(docutils.square.sqrt(49), 7)
            self.assertEqual(docutils.square.sqrt(0), 0)
            self.assertRaises(docutils.square.SquareRootError,
                              docutils.square.sqrt, 20)


    if __name__ == '__main__':
        unittest.main()

For more details on how to write tests, please refer to the
documentation of the ``unittest`` module.

.. Note::

   Unit tests and functional test should generally set ::

     settings_overrides['_disable_config'] = True

   in order to be independent on the users local configuration.

.. _functional:

Functional Tests
================

The directory ``test/functional/`` contains data for functional tests.

Performing functional testing means testing the Docutils system as a
whole (i.e. blackbox testing).


Directory Structure
-------------------

+ ``functional/`` The main data directory.

  + ``input/`` The input files.

    - ``some_test.txt``, for example.

  + ``output/`` The actual output.

    - ``some_test.html``, for example.

  + ``expected/`` The expected output.

    - ``some_test.html``, for example.

  + ``tests/`` The config files for processing the input files.

    - ``some_test.py``, for example.

    - ``_default.py``, the `default configuration file`_.


The Testing Process
-------------------

When running ``test_functional.py``, all config files in
``functional/tests/`` are processed.  (Config files whose names begin
with an underscore are ignored.)  The current working directory is
always Docutils' main test directory (``test/``).

For example, ``functional/tests/some_test.py`` could read like this::

    # Source and destination file names.
    test_source = "some_test.txt"
    test_destination = "some_test.html"

    # Keyword parameters passed to publish_file.
    reader_name = "standalone"
    parser_name = "rst"
    writer_name = "html"
    settings_overrides['output-encoding'] = 'utf-8'
    # Relative to main ``test/`` directory.
    settings_overrides['stylesheet_path'] = '../docutils/writers/html4css1/html4css1.css'

The two variables ``test_source`` and ``test_destination`` contain the
input file name (relative to ``functional/input/``) and the output
file name (relative to ``functional/output/`` and
``functional/expected/``).  Note that the file names can be chosen
arbitrarily.  However, the file names in ``functional/output/`` *must*
match the file names in ``functional/expected/``.

If defined, ``_test_more`` must be a function with the following
signature::

    def _test_more(expected_dir, output_dir, test_case, parameters):

This function is called from the test case to perform tests beyond the
simple comparison of expected and actual output files.

``test_source`` and ``test_destination`` are removed from the
namespace, as are all variables whose names begin with an underscore
("_").  The remaining names are passed as keyword arguments to
``docutils.core.publish_file``, so you can set reader, parser, writer
and anything else you want to configure.  Note that
``settings_overrides`` is already initialized as a dictionary *before*
the execution of the config file.


Creating New Tests
------------------

In order to create a new test, put the input test file into
``functional/input/``.  Then create a config file in
``functional/tests/`` which sets at least input and output file names,
reader, parser and writer.

Now run ``test_functional.py``.  The test will fail, of course,
because you do not have an expected output yet.  However, an output
file will have been generated in ``functional/output/``.  Check this
output file for validity [#]_ and correctness.  Then copy the file to
``functional/expected/``.

If you rerun ``test_functional.py`` now, it should pass.

If you run ``test_functional.py`` later and the actual output doesn't
match the expected output anymore, the test will fail.

If this is the case and you made an intentional change, check the
actual output for validity and correctness, copy it to
``functional/expected/`` (overwriting the old expected output), and
commit the change.

.. [#] The validity of `Docutils XML` can be tested with
   ``xmllint <document-referencing-local-Docutils-DTD>.xml --valid --noout``.
     
   .. note: the ``--dtdvalid`` and ``--nonet`` options did not help override
     a reference to the PUBLIC "docutils.dtd" if there is a local version
     on the system (e.g. /usr/share/xml/docutils/docutils.dtd in Debian).


.. _default configuration file:

The Default Configuration File
------------------------------

The file ``functional/tests/_default.py`` contains default settings.
It is executed just before the actual configuration files, which has
the same effect as if the contents of ``_default.py`` were prepended
to every configuration file.
