Unit tests

Django comes with a test suite of its own, in the tests directory of the code base. It’s our policy to make sure all tests pass at all times.

We appreciate any and all contributions to the test suite!

The Django tests all use the testing infrastructure that ships with Django for testing applications. See Writing and running tests for an explanation of how to write new tests.

Running the unit tests

Quickstart

If you are on Python 2, you’ll first need to install a backport of the unittest.mock module that’s available in Python 3. See Running all the tests for details on installing mock and the other optional test dependencies.

Running the tests requires a Django settings module that defines the databases to use. To make it easy to get started, Django provides and uses a sample settings module that uses the SQLite database. To run the tests:

$ git clone https://github.com/django/django.git django-repo
$ cd django-repo/tests
$ PYTHONPATH=..:$PYTHONPATH ./runtests.py

Windows users

We recommend something like Git Bash to run the tests using the above approach.

You can avoid typing the PYTHONPATH bit each time by adding your Django checkout to your PYTHONPATH or by installing the source checkout using pip. See Installing the development version.

Having problems? See Troubleshooting for some common issues.

Using another settings module

The included settings module allows you to run the test suite using SQLite. If you want to test behavior using a different database (and if you’re proposing patches for Django, it’s a good idea to test across databases), you may need to define your own settings file.

To run the tests with different settings, ensure that the module is on your PYTHONPATH and pass the module with --settings.

The DATABASES setting in any test settings module needs to define two databases:

  • A default database. This database should use the backend that you want to use for primary testing
  • A database with the alias other. The other database is used to establish that queries can be directed to different databases. As a result, this database can use any backend you want. It doesn’t need to use the same backend as the default database (although it can use the same backend if you want to). It cannot be the same database as the default.

If you’re using a backend that isn’t SQLite, you will need to provide other details for each database:

  • The USER option needs to specify an existing user account for the database. That user needs permission to execute CREATE DATABASE so that the test database can be created.
  • The PASSWORD option needs to provide the password for the USER that has been specified.

Test databases get their names by prepending test_ to the value of the NAME settings for the databases defined in DATABASES. These test databases are deleted when the tests are finished.

You will also need to ensure that your database uses UTF-8 as the default character set. If your database server doesn’t use UTF-8 as a default charset, you will need to include a value for TEST_CHARSET in the settings dictionary for the applicable database.

Running only some of the tests

Django’s entire test suite takes a while to run, and running every single test could be redundant if, say, you just added a test to Django that you want to run quickly without running everything else. You can run a subset of the unit tests by appending the names of the test modules to runtests.py on the command line.

For example, if you’d like to run tests only for generic relations and internationalization, type:

$ ./runtests.py --settings=path.to.settings generic_relations i18n

How do you find out the names of individual tests? Look in tests/ — each directory name there is the name of a test.

If you just want to run a particular class of tests, you can specify a list of paths to individual test classes. For example, to run the TranslationTests of the i18n module, type:

$ ./runtests.py --settings=path.to.settings i18n.tests.TranslationTests

Going beyond that, you can specify an individual test method like this:

$ ./runtests.py --settings=path.to.settings i18n.tests.TranslationTests.test_lazy_objects

Running the Selenium tests

Some tests require Selenium and a Web browser (Firefox, Google Chrome, or Internet Explorer). To allow those tests to be run rather than skipped, you must install the selenium package into your Python path and run the tests with the --selenium option:

$ ./runtests.py --settings=test_sqlite --selenium admin_inlines

Running all the tests

If you want to run the full suite of tests, you’ll need to install a number of dependencies:

You can find these dependencies in pip requirements files inside the tests/requirements directory of the Django source tree and install them like so:

$ pip install -r tests/requirements/py3.txt  # Python 2: py2.txt

You can also install the database adapter(s) of your choice using oracle.txt, mysql.txt, or postgres.txt.

If you want to test the memcached cache backend, you’ll also need to define a CACHES setting that points at your memcached instance.

To run the GeoDjango tests, you will need to setup a spatial database and install the Geospatial libraries.

Each of these dependencies is optional. If you’re missing any of them, the associated tests will be skipped.

Code coverage

Contributors are encouraged to run coverage on the test suite to identify areas that need additional tests. The coverage tool installation and use is described in testing code coverage.

To run coverage on the Django test suite using the standard test settings:

$ coverage run ./runtests.py --settings=test_sqlite

After running coverage, generate the html report by running:

$ coverage html

When running coverage for the Django tests, the included .coveragerc settings file defines coverage_html as the output directory for the report and also excludes several directories not relevant to the results (test code or external code included in Django).

Contrib apps

Tests for contrib apps can be found in the tests/ directory, typically under <app_name>_tests. For example, tests for contrib.auth are located in tests/auth_tests.

Troubleshooting

Many test failures with UnicodeEncodeError

If the locales package is not installed, some tests will fail with a UnicodeEncodeError.

You can resolve this on Debian-based systems, for example, by running:

$ apt-get install locales
$ dpkg-reconfigure locales

Tests that only fail in combination

In case a test passes when run in isolation but fails within the whole suite, we have some tools to help analyze the problem.

The --bisect option of runtests.py will run the failing test while halving the test set it is run together with on each iteration, often making it possible to identify a small number of tests that may be related to the failure.

For example, suppose that the failing test that works on its own is ModelTest.test_eq, then using:

$ ./runtests.py --bisect basic.tests.ModelTest.test_eq

will try to determine a test that interferes with the given one. First, the test is run with the first half of the test suite. If a failure occurs, the first half of the test suite is split in two groups and each group is then run with the specified test. If there is no failure with the first half of the test suite, the second half of the test suite is run with the specified test and split appropriately as described earlier. The process repeats until the set of failing tests is minimized.

The --pair option runs the given test alongside every other test from the suite, letting you check if another test has side-effects that cause the failure. So:

$ ./runtests.py --pair basic.tests.ModelTest.test_eq

will pair test_eq with every test label.

With both --bisect and --pair, if you already suspect which cases might be responsible for the failure, you may limit tests to be cross-analyzed by specifying further test labels after the first one:

$ ./runtests.py --pair basic.tests.ModelTest.test_eq queries transactions

You can also try running any set of tests in reverse using the --reverse option in order to verify that executing tests in a different order does not cause any trouble:

$ ./runtests.py basic --reverse

If you wish to examine the SQL being run in failing tests, you can turn on SQL logging using the --debug-sql option. If you combine this with --verbosity=2, all SQL queries will be output:

$ ./runtests.py basic --debug-sql
New in Django 1.8:

The --reverse and --debug-sql options were added.

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