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¶
First, fork Django on GitHub.
Second, create and activate a virtual environment. If you’re not familiar with how to do that, read our contributing tutorial.
Next, clone your fork, install some requirements, and run the tests:
$ git clone https://github.com/YourGitHubName/django.git django-repo $ cd django-repo/tests $ python -m pip install -e .. $ python -m pip install -r requirements/py3.txt $ ./runtests.py
...\> git clone https://github.com/YourGitHubName/django.git django-repo ...\> cd django-repo\tests ...\> py -m pip install -e .. ...\> py -m pip install -r requirements\py3.txt ...\> runtests.py
Installing the requirements will likely require some operating system packages that your computer doesn’t have installed. You can usually figure out which package to install by doing a Web search for the last line or so of the error message. Try adding your operating system to the search query if needed.
If you have trouble installing the requirements, you can skip that step. See Running all the tests for details on installing the optional test dependencies. If you don’t have an optional dependency installed, the tests that require it will be skipped.
Running the tests requires a Django settings module that defines the databases to use. To help you get started, Django provides and uses a sample settings module that uses the SQLite database. See Using another settings module to learn how to use a different settings module to run the tests with a different database.
Having problems? See Troubleshooting for some common issues.
Running tests using
Tox is a tool for running tests in different
virtual environments. Django includes a basic
tox.ini that automates some
checks that our build server performs on pull requests. To run the unit tests
and other checks (such as import sorting, the
documentation spelling checker, and
code formatting), install and run the
command from any place in the Django source tree:
$ python -m pip install tox $ tox
...\> py -m pip install tox ...\> tox
tox runs the test suite with the bundled test settings file for
isort, and the documentation spelling checker. In
addition to the system dependencies noted elsewhere in this documentation,
python3 must be on your path and linked to the appropriate
version of Python. A list of default environments can be seen as follows:
$ tox -l py3 flake8 docs isort>=5.1.0
...\> tox -l py3 flake8 docs isort>=5.1.0
Testing other Python versions and database backends¶
In addition to the default environments,
tox supports running unit tests
for other versions of Python and other database backends. Since Django’s test
suite doesn’t bundle a settings file for database backends other than SQLite,
however, you must create and provide your own test settings. For example, to run the tests on Python 3.9
$ tox -e py39-postgres -- --settings=my_postgres_settings
...\> tox -e py39-postgres -- --settings=my_postgres_settings
This command sets up a Python 3.9 virtual environment, installs Django’s
test suite dependencies (including those for PostgreSQL), and calls
runtests.py with the supplied arguments (in this case,
The remainder of this documentation shows commands for running tests without
tox, however, any option passed to
runtests.py can also be passed to
tox by prefixing the argument list with
--, as above.
Tox also respects the
DJANGO_SETTINGS_MODULE environment variable, if
set. For example, the following is equivalent to the command above:
$ DJANGO_SETTINGS_MODULE=my_postgres_settings tox -e py39-postgres
Windows users should use:
...\> set DJANGO_SETTINGS_MODULE=my_postgres_settings ...\> tox -e py39-postgres
tox because they require
Node.js to be installed and aren’t
This command runs
npm install to ensure test requirements are up to
date and then runs
Running tests using
The included settings module (
tests/test_sqlite.py) allows you to run the
test suite using SQLite. If you want to run the tests using a different
database, you’ll need to define your own settings file. Some tests, such as
contrib.postgres, are specific to a particular database backend
and will be skipped if run with a different backend. Some tests are skipped or
expected failures on a particular database backend (see
DatabaseFeatures.django_test_expected_failures on each backend).
To run the tests with different settings, ensure that the module is on your
PYTHONPATH and pass the module with
DATABASES setting in any test settings module needs to define
defaultdatabase. This database should use the backend that you want to use for primary testing.
- A database with the alias
otherdatabase is used to test that queries can be directed to different databases. This database should use the same backend as the
default, and it must have a different name.
If you’re using a backend that isn’t SQLite, you will need to provide other details for each database:
USERoption needs to specify an existing user account for the database. That user needs permission to execute
CREATE DATABASEso that the test database can be created.
PASSWORDoption needs to provide the password for the
USERthat has been specified.
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
CHARSET in the
test 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
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
...\> 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 want to run only a particular class of tests, you can specify a list of
paths to individual test classes. For example, to run the
i18n module, type:
$ ./runtests.py --settings=path.to.settings i18n.tests.TranslationTests
...\> 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
...\> runtests.py --settings=path.to.settings i18n.tests.TranslationTests.test_lazy_objects
You can run tests starting at a specified top-level module with
option. For example:
$ ./runtests.py --start-at=wsgi
...\> runtests.py --start-at=wsgi
You can also run tests starting after a specified top-level module with
--start-after option. For example:
$ ./runtests.py --start-after=wsgi
...\> runtests.py --start-after=wsgi
Note that the
--reverse option doesn’t impact on
--start-after options. Moreover these options cannot be used with test
Running the Selenium tests¶
Some tests require Selenium and a Web browser. To run these tests, you must
install the selenium package and run the tests with the
--selenium=<BROWSERS> option. For example, if you have Firefox and Google
$ ./runtests.py --selenium=firefox,chrome
...\> runtests.py --selenium=firefox,chrome
See the selenium.webdriver package for the list of available browsers.
--selenium automatically sets
--tags=selenium to run only
the tests that require selenium.
Some browsers (e.g. Chrome or Firefox) support headless testing, which can be
faster and more stable. Add the
--headless option to enable this mode.
Running all the tests¶
If you want to run the full suite of tests, you’ll need to install a number of dependencies:
- argon2-cffi 19.1.0+
- asgiref 3.3.2+ (required)
- jinja2 2.7+
- Pillow 6.2.0+
- pytz (required)
- memcached, plus a supported Python binding
- gettext (gettext on Windows)
- sqlparse 0.2.2+ (required)
- tblib 1.5.0+
You can find these dependencies in pip requirements files inside the
tests/requirements directory of the Django source tree and install them
$ python -m pip install -r tests/requirements/py3.txt
...\> py -m pip install -r tests\requirements\py3.txt
If you encounter an error during the installation, your system might be missing a dependency for one or more of the Python packages. Consult the failing package’s documentation or search the Web with the error message that you encounter.
You can also install the database adapter(s) of your choice using
If you want to test the memcached cache backend, you’ll also need to define
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.
To run some of the autoreload tests, you’ll need to install the Watchman service.
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.
Coverage should be run in a single process to obtain accurate statistics. To run coverage on the Django test suite using the standard test settings:
$ coverage run ./runtests.py --settings=test_sqlite --parallel=1
...\> coverage run runtests.py --settings=test_sqlite --parallel=1
After running coverage, generate the html report by running:
$ coverage html
...\> coverage html
When running coverage for the Django tests, the included
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).
Tests for contrib apps can be found in the
tests/ directory, typically
<app_name>_tests. For example, tests for
contrib.auth are located
Test suite hangs or shows failures on
Ensure you have the latest point release of a supported Python version, since there are often bugs in earlier versions that may cause the test suite to fail or hang.
On macOS (High Sierra and newer versions), you might see this message logged, after which the tests hang:
objc: +[__NSPlaceholderDate initialize] may have been in progress in another thread when fork() was called.
To avoid this set a
variable, for example:
$ OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES ./runtests.py
export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES to your shell’s
startup file (e.g.
Many test failures with
locales package is not installed, some tests will fail with a
You can resolve this on Debian-based systems, for example, by running:
$ apt-get install locales $ dpkg-reconfigure locales
You can resolve this for macOS systems by configuring your shell’s locale:
$ export LANG="en_US.UTF-8" $ export LC_ALL="en_US.UTF-8"
locale command to confirm the change. Optionally, add those export
commands to your shell’s startup file (e.g.
~/.bashrc for Bash) to avoid
having to retype them.
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.
--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
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
...\> 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.
--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
$ ./runtests.py --pair basic.tests.ModelTest.test_eq
...\> runtests.py --pair basic.tests.ModelTest.test_eq
test_eq with every test label.
--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
...\> runtests.py --pair basic.tests.ModelTest.test_eq queries transactions
You can also try running any set of tests in reverse using the
option in order to verify that executing tests in a different order does not
cause any trouble:
$ ./runtests.py basic --reverse
...\> runtests.py basic --reverse
Seeing the SQL queries run during a test¶
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
...\> runtests.py basic --debug-sql
Seeing the full traceback of a test failure¶
By default tests are run in parallel with one process per core. When the tests
are run in parallel, however, you’ll only see a truncated traceback for any
test failures. You can adjust this behavior with the
$ ./runtests.py basic --parallel=1
...\> runtests.py basic --parallel=1
You can also use the
DJANGO_TEST_PROCESSES environment variable for
Tips for writing tests¶
Isolating model registration¶
To avoid polluting the global
apps registry and prevent
unnecessary table creation, models defined in a test method should be bound to
from django.apps.registry import Apps from django.db import models from django.test import SimpleTestCase class TestModelDefinition(SimpleTestCase): def test_model_definition(self): test_apps = Apps(['app_label']) class TestModel(models.Model): class Meta: apps = test_apps ...
isolate_apps(*app_labels, attr_name=None, kwarg_name=None)¶
Since this pattern involves a lot of boilerplate, Django provides the
isolate_apps() decorator. It’s used like this:
from django.db import models from django.test import SimpleTestCase from django.test.utils import isolate_apps class TestModelDefinition(SimpleTestCase): @isolate_apps('app_label') def test_model_definition(self): class TestModel(models.Model): pass ...
Models defined in a test method with no explicit
app_label are automatically assigned the
label of the app in which their test class is located.
In order to make sure the models defined within the context of
isolate_apps() instances are correctly
installed, you should pass the set of targeted
app_label as arguments:
from django.db import models from django.test import SimpleTestCase from django.test.utils import isolate_apps class TestModelDefinition(SimpleTestCase): @isolate_apps('app_label', 'other_app_label') def test_model_definition(self): # This model automatically receives app_label='app_label' class TestModel(models.Model): pass class OtherAppModel(models.Model): class Meta: app_label = 'other_app_label' ...
The decorator can also be applied to classes:
from django.db import models from django.test import SimpleTestCase from django.test.utils import isolate_apps @isolate_apps('app_label') class TestModelDefinition(SimpleTestCase): def test_model_definition(self): class TestModel(models.Model): pass ...
Apps instance used to isolate model registration can be
retrieved as an attribute when used as a class decorator by using the
from django.db import models from django.test import SimpleTestCase from django.test.utils import isolate_apps @isolate_apps('app_label', attr_name='apps') class TestModelDefinition(SimpleTestCase): def test_model_definition(self): class TestModel(models.Model): pass self.assertIs(self.apps.get_model('app_label', 'TestModel'), TestModel)
Or as an argument on the test method when used as a method decorator by using
from django.db import models from django.test import SimpleTestCase from django.test.utils import isolate_apps class TestModelDefinition(SimpleTestCase): @isolate_apps('app_label', kwarg_name='apps') def test_model_definition(self, apps): class TestModel(models.Model): pass self.assertIs(apps.get_model('app_label', 'TestModel'), TestModel)