fixture is a python module for loading and referencing test data
It provides several utilities for achieving a fixed state when testing Python programs. Specifically, these utilities setup / teardown databases and work with temporary file systems. This is useful for testing and came about to fulfill stories like these:
For more info, this concept is explained in the wikipedia article, Test Fixture.
Database testing is easier than I had thought. Kumar’s fixture helps provide a stable database to drive testing. – Steven F. Lott, summarizing PyCon 2007
Using the easy_install command:
pip install fixture
The above commands may require root access
For more variants on the easy_install command, such as installing database libraries, see Using LoadableFixture.
cd /path/to/source python setup.py install
To run Fixture’s own test suite you need to create a buildout
python setup_test_buildout.py ./bin/buildout
Then you can run the tests with
At the moment fixture is only tested on Python 2.4, 2.5, and 2.6 so it may or may not work with other versions. The module does not depend on external libraries for its core functionality but to do something interesting you will need one of several 3rd party libraries (explained later in the documentation).
There are a couple ways to test a database-backed application. You can create mock objects and concentrate entirely on unit testing individual components without testing the database layer itself, or you can simply load up sample data before you run a test. Thanks to sqlite in-memory connections, the latter may be more efficient than you think.
But it’s easy enough to insert data line by line in code, right? Or simply load a SQL file? Yes, but this has two major downsides: you often have to worry about and manage complex chains of foreign keys manually; and when referencing data values later on, you either have to copy / paste the values or pass around lots of variables.
The fixture module simplifies this by breaking the process down to two independent components:
Fixture can be used to load DataSet objects into the following backends:
You can read the section on loading data for general information. For a complete end-to-end example see Using Fixture To Test A Pylons + SQLAlchemy App, Using Fixture To Test A Google App Engine Site or Using Fixture To Test Django. This should help you understand how to fit fixture into a finished app.
Now, on to the knitty gritty details ...
fixture was originally a reimplementation of testtools.fixtures, the first attempt at the idea. As of September 2009 the fixture module is used in several test suites by the author’s development team at work using the SQLAlchemy backend. Several contributors seem to be using it in their own projects as well for various backends like Google App Engine and Django. The project started in 2007.