Fixed #4501 - Documented how to use coverage.py with Django tests.

Don't forget to also include in :setting:`PASSWORD_HASHERS` any hashing

algorithm used in fixtures, if any.

Integration with coverage.py

----------------------------

Code coverage describes how much source code has been tested. It shows which

parts of your code are being exercised by tests and which are not. It's an

important part of testing applications, so it's strongly recommended to check

the coverage of your tests.

Django can be easily integrated with `coverage.py`_, a tool for measuring code

coverage of Python programs. First, `install coverage.py`_. Next, run the

following from your project folder containing ``manage.py``::

   coverage run --source='.' manage.py test myapp

This runs your tests and collects coverage data of the executed files in your

project. You can see a report of this data by typing following command::

   coverage report

Note that some Django code was executed while running tests, but it is not

listed here because of the ``source`` flag passed to the previous command.

For more options like annotated HTML listings detailing missed lines, see the

`coverage.py`_ docs.

.. _coverage.py: http://nedbatchelder.com/code/coverage/

.. _install coverage.py: http://pypi.python.org/pypi/coverage

Testing tools

=============