pytest-randomly 1.0.0

Pytest plugin to randomly order tests and control random.seed.

===============
pytest-randomly
===============

.. image:: https://img.shields.io/travis/adamchainz/pytest-randomly.svg
:target: https://travis-ci.org/adamchainz/pytest-randomly

.. image:: https://img.shields.io/pypi/v/pytest-randomly.svg
:target: https://pypi.python.org/pypi/pytest-randomly

.. figure:: https://raw.githubusercontent.com/adamchainz/pytest-randomly/master/logo.png
:scale: 50%
:alt: Randomness power.

Pytest plugin to randomly order tests and control ``random.seed``. (Also
available `for nose <https://github.com/adamchainz/nose-randomly>`_).

Features
--------

All of these features are on by default but can be disabled with flags.

* Randomly shuffles the order of test items. This is done first at the level of
modules, then at the level of test classes (if you have them), then at the
order of functions. This also works with things like doctests.
* Resets ``random.seed()`` at the start of every test case and test to a fixed
number - this defaults to ``time.time()`` from the start of your test run,
but you can pass in ``--randomly-seed`` to repeat a randomness-induced
failure.
* If
`factory boy <https://factoryboy.readthedocs.org/en/latest/reference.html>`_
is installed, its random state is reset at the start of every test. This
allows for repeatable use of its random 'fuzzy' features.
* If `faker <https://pypi.python.org/pypi/fake-factory>`_ is installed, its
random state is reset at the start of every test. This is also for repeatable
fuzzy data in tests - factory boy uses faker for lots of data.

About
-----

Randomness in testing can be quite powerful to discover hidden flaws in the
tests themselves, as well as giving a little more coverage to your system.

By randomly ordering the tests, the risk of surprising inter-test dependencies
is reduced - a technique used in many places, for example Google's C++ test
runner `googletest
<https://code.google.com/p/googletest/wiki/V1_5_AdvancedGuide#Shuffling_the_Tests>`_.

By resetting the random seed to a repeatable number for each test, tests can
create data based on random numbers and yet remain repeatable, for example
factory boy's fuzzy values. This is good for ensuring that tests specify the
data they need and that the tested system is not affected by any data that is
filled in randomly due to not being specified.

This plugin is a Pytest port of my plugin for nose, ``nose-randomly``.

Usage
-----

Install from pip with:

.. code-block:: bash

pip install pytest-randomly

Pytest will automatically find the plugin and use it when you run ``py.test``.
The output will start with an extra line that tells you the random seed that is
being used:

.. code-block:: bash

$ py.test
platform darwin -- Python 2.7.11, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
Using --randomly-seed=1460130750
...

If the tests fail due to ordering or randomly created data, you can restart
them with that seed using the flag as suggested:

.. code-block:: bash

py.test --randomly-seed=1234

You can disable behaviours you don't like with the following flags:

* ``--randomly-dont-reset-seed`` - turn off the reset of ``random.seed()`` at
the start of every test
* ``--randomly-dont-reorganize`` - turn off the shuffling of the order of tests

The plugin appears to Pytest with the name 'randomly'. To disable it
altogether, you can use the ``-p`` argument, for example:

.. code-block:: sh

py.test -p no:randomly




History
-------

Pending Release
---------------

* New release notes here

1.0.0 (2016-04-15)
------------------

* First release on PyPI.