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Thanks to Preston Timmons for the bulk of the work on the patch, especially updating Django's own test suite to comply with the requirements of the new runner. Thanks also to Jannis Leidel and Mahdi Yusuf for earlier work on the patch and the discovery runner. Refs #11077, #17032, and #18670.
447 lines
16 KiB
Plaintext
447 lines
16 KiB
Plaintext
=======================
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Advanced testing topics
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=======================
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The request factory
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===================
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.. module:: django.test.client
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.. class:: RequestFactory
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The :class:`~django.test.client.RequestFactory` shares the same API as
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the test client. However, instead of behaving like a browser, the
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RequestFactory provides a way to generate a request instance that can
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be used as the first argument to any view. This means you can test a
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view function the same way as you would test any other function -- as
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a black box, with exactly known inputs, testing for specific outputs.
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The API for the :class:`~django.test.client.RequestFactory` is a slightly
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restricted subset of the test client API:
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* It only has access to the HTTP methods :meth:`~Client.get()`,
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:meth:`~Client.post()`, :meth:`~Client.put()`,
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:meth:`~Client.delete()`, :meth:`~Client.head()` and
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:meth:`~Client.options()`.
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* These methods accept all the same arguments *except* for
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``follows``. Since this is just a factory for producing
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requests, it's up to you to handle the response.
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* It does not support middleware. Session and authentication
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attributes must be supplied by the test itself if required
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for the view to function properly.
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Example
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-------
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The following is a simple unit test using the request factory::
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from django.utils import unittest
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from django.test.client import RequestFactory
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class SimpleTest(unittest.TestCase):
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def setUp(self):
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# Every test needs access to the request factory.
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self.factory = RequestFactory()
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def test_details(self):
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# Create an instance of a GET request.
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request = self.factory.get('/customer/details')
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# Test my_view() as if it were deployed at /customer/details
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response = my_view(request)
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self.assertEqual(response.status_code, 200)
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.. _topics-testing-advanced-multidb:
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Tests and multiple databases
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============================
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.. _topics-testing-masterslave:
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Testing master/slave configurations
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-----------------------------------
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If you're testing a multiple database configuration with master/slave
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replication, this strategy of creating test databases poses a problem.
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When the test databases are created, there won't be any replication,
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and as a result, data created on the master won't be seen on the
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slave.
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To compensate for this, Django allows you to define that a database is
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a *test mirror*. Consider the following (simplified) example database
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configuration::
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DATABASES = {
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'default': {
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'ENGINE': 'django.db.backends.mysql',
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'NAME': 'myproject',
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'HOST': 'dbmaster',
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# ... plus some other settings
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},
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'slave': {
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'ENGINE': 'django.db.backends.mysql',
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'NAME': 'myproject',
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'HOST': 'dbslave',
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'TEST_MIRROR': 'default'
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# ... plus some other settings
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}
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}
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In this setup, we have two database servers: ``dbmaster``, described
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by the database alias ``default``, and ``dbslave`` described by the
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alias ``slave``. As you might expect, ``dbslave`` has been configured
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by the database administrator as a read slave of ``dbmaster``, so in
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normal activity, any write to ``default`` will appear on ``slave``.
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If Django created two independent test databases, this would break any
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tests that expected replication to occur. However, the ``slave``
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database has been configured as a test mirror (using the
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:setting:`TEST_MIRROR` setting), indicating that under testing,
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``slave`` should be treated as a mirror of ``default``.
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When the test environment is configured, a test version of ``slave``
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will *not* be created. Instead the connection to ``slave``
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will be redirected to point at ``default``. As a result, writes to
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``default`` will appear on ``slave`` -- but because they are actually
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the same database, not because there is data replication between the
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two databases.
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.. _topics-testing-creation-dependencies:
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Controlling creation order for test databases
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---------------------------------------------
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By default, Django will always create the ``default`` database first.
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However, no guarantees are made on the creation order of any other
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databases in your test setup.
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If your database configuration requires a specific creation order, you
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can specify the dependencies that exist using the
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:setting:`TEST_DEPENDENCIES` setting. Consider the following
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(simplified) example database configuration::
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DATABASES = {
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'default': {
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# ... db settings
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'TEST_DEPENDENCIES': ['diamonds']
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},
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'diamonds': {
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# ... db settings
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},
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'clubs': {
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# ... db settings
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'TEST_DEPENDENCIES': ['diamonds']
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},
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'spades': {
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# ... db settings
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'TEST_DEPENDENCIES': ['diamonds','hearts']
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},
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'hearts': {
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# ... db settings
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'TEST_DEPENDENCIES': ['diamonds','clubs']
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}
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}
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Under this configuration, the ``diamonds`` database will be created first,
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as it is the only database alias without dependencies. The ``default`` and
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``clubs`` alias will be created next (although the order of creation of this
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pair is not guaranteed); then ``hearts``; and finally ``spades``.
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If there are any circular dependencies in the
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:setting:`TEST_DEPENDENCIES` definition, an ``ImproperlyConfigured``
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exception will be raised.
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Running tests outside the test runner
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=====================================
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If you want to run tests outside of ``./manage.py test`` -- for example,
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from a shell prompt -- you will need to set up the test
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environment first. Django provides a convenience method to do this::
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>>> from django.test.utils import setup_test_environment
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>>> setup_test_environment()
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:func:`~django.test.utils.setup_test_environment` puts several Django features
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into modes that allow for repeatable testing, but does not create the test
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databases; :func:`django.test.runner.DiscoverRunner.setup_databases`
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takes care of that.
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The call to :func:`~django.test.utils.setup_test_environment` is made
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automatically as part of the setup of ``./manage.py test``. You only
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need to manually invoke this method if you're not using running your
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tests via Django's test runner.
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.. _other-testing-frameworks:
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Using different testing frameworks
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==================================
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Clearly, :mod:`unittest` is not the only Python testing framework. While Django
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doesn't provide explicit support for alternative frameworks, it does provide a
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way to invoke tests constructed for an alternative framework as if they were
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normal Django tests.
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When you run ``./manage.py test``, Django looks at the :setting:`TEST_RUNNER`
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setting to determine what to do. By default, :setting:`TEST_RUNNER` points to
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``'django.test.runner.DiscoverRunner'``. This class defines the default Django
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testing behavior. This behavior involves:
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#. Performing global pre-test setup.
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#. Looking for tests in any file below the current directory whose name matches
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the pattern ``test*.py``.
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#. Creating the test databases.
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#. Running ``syncdb`` to install models and initial data into the test
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databases.
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#. Running the tests that were found.
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#. Destroying the test databases.
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#. Performing global post-test teardown.
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If you define your own test runner class and point :setting:`TEST_RUNNER` at
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that class, Django will execute your test runner whenever you run
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``./manage.py test``. In this way, it is possible to use any test framework
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that can be executed from Python code, or to modify the Django test execution
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process to satisfy whatever testing requirements you may have.
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.. _topics-testing-test_runner:
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Defining a test runner
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----------------------
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.. currentmodule:: django.test.runner
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A test runner is a class defining a ``run_tests()`` method. Django ships
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with a ``DiscoverRunner`` class that defines the default Django
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testing behavior. This class defines the ``run_tests()`` entry point,
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plus a selection of other methods that are used to by ``run_tests()`` to
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set up, execute and tear down the test suite.
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.. class:: DiscoverRunner(pattern='test*.py', top_level=None, verbosity=1, interactive=True, failfast=True, **kwargs)
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``DiscoverRunner`` will search for tests in any file matching ``pattern``.
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``top_level`` can be used to specify the directory containing your
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top-level Python modules. Usually Django can figure this out automatically,
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so it's not necessary to specify this option. If specified, it should
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generally be the directory containing your ``manage.py`` file.
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``verbosity`` determines the amount of notification and debug information
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that will be printed to the console; ``0`` is no output, ``1`` is normal
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output, and ``2`` is verbose output.
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If ``interactive`` is ``True``, the test suite has permission to ask the
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user for instructions when the test suite is executed. An example of this
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behavior would be asking for permission to delete an existing test
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database. If ``interactive`` is ``False``, the test suite must be able to
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run without any manual intervention.
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If ``failfast`` is ``True``, the test suite will stop running after the
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first test failure is detected.
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Django may, from time to time, extend the capabilities of the test runner
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by adding new arguments. The ``**kwargs`` declaration allows for this
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expansion. If you subclass ``DiscoverRunner`` or write your own test
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runner, ensure it accepts ``**kwargs``.
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Your test runner may also define additional command-line options.
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If you add an ``option_list`` attribute to a subclassed test runner,
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those options will be added to the list of command-line options that
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the :djadmin:`test` command can use.
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Attributes
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~~~~~~~~~~
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.. attribute:: DiscoverRunner.option_list
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This is the tuple of ``optparse`` options which will be fed into the
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management command's ``OptionParser`` for parsing arguments. See the
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documentation for Python's ``optparse`` module for more details.
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Methods
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~~~~~~~
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.. method:: DiscoverRunner.run_tests(test_labels, extra_tests=None, **kwargs)
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Run the test suite.
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``test_labels`` is a list of strings describing the tests to be run. A test
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label can take one of four forms:
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* ``path.to.test_module.TestCase.test_method`` -- Run a single test method
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in a test case.
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* ``path.to.test_module.TestCase`` -- Run all the test methods in a test
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case.
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* ``path.to.module`` -- Search for and run all tests in the named Python
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package or module.
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* ``path/to/directory`` -- Search for and run all tests below the named
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directory.
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If ``test_labels`` has a value of ``None``, the test runner will search for
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tests in all files below the current directory whose names match its
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``pattern`` (see above).
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``extra_tests`` is a list of extra ``TestCase`` instances to add to the
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suite that is executed by the test runner. These extra tests are run
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in addition to those discovered in the modules listed in ``test_labels``.
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This method should return the number of tests that failed.
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.. method:: DiscoverRunner.setup_test_environment(**kwargs)
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Sets up the test environment by calling
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:func:`~django.test.utils.setup_test_environment` and setting
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:setting:`DEBUG` to ``False``.
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.. method:: DiscoverRunner.build_suite(test_labels, extra_tests=None, **kwargs)
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Constructs a test suite that matches the test labels provided.
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``test_labels`` is a list of strings describing the tests to be run. A test
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label can take one of three forms:
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* ``app.TestCase.test_method`` -- Run a single test method in a test
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case.
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* ``app.TestCase`` -- Run all the test methods in a test case.
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* ``app`` -- Search for and run all tests in the named application.
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If ``test_labels`` has a value of ``None``, the test runner should run
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search for tests in all the applications in :setting:`INSTALLED_APPS`.
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``extra_tests`` is a list of extra ``TestCase`` instances to add to the
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suite that is executed by the test runner. These extra tests are run
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in addition to those discovered in the modules listed in ``test_labels``.
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Returns a ``TestSuite`` instance ready to be run.
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.. method:: DiscoverRunner.setup_databases(**kwargs)
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Creates the test databases.
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Returns a data structure that provides enough detail to undo the changes
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that have been made. This data will be provided to the ``teardown_databases()``
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function at the conclusion of testing.
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.. method:: DiscoverRunner.run_suite(suite, **kwargs)
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Runs the test suite.
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Returns the result produced by the running the test suite.
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.. method:: DiscoverRunner.teardown_databases(old_config, **kwargs)
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Destroys the test databases, restoring pre-test conditions.
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``old_config`` is a data structure defining the changes in the
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database configuration that need to be reversed. It is the return
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value of the ``setup_databases()`` method.
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.. method:: DiscoverRunner.teardown_test_environment(**kwargs)
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Restores the pre-test environment.
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.. method:: DiscoverRunner.suite_result(suite, result, **kwargs)
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Computes and returns a return code based on a test suite, and the result
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from that test suite.
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Testing utilities
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-----------------
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django.test.utils
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~~~~~~~~~~~~~~~~~
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.. module:: django.test.utils
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:synopsis: Helpers to write custom test runners.
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To assist in the creation of your own test runner, Django provides a number of
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utility methods in the ``django.test.utils`` module.
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.. function:: setup_test_environment()
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Performs any global pre-test setup, such as the installing the
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instrumentation of the template rendering system and setting up
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the dummy email outbox.
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.. function:: teardown_test_environment()
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Performs any global post-test teardown, such as removing the black
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magic hooks into the template system and restoring normal email
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services.
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django.db.connection.creation
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. currentmodule:: django.db.connection.creation
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The creation module of the database backend also provides some utilities that
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can be useful during testing.
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.. function:: create_test_db([verbosity=1, autoclobber=False])
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Creates a new test database and runs ``syncdb`` against it.
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``verbosity`` has the same behavior as in ``run_tests()``.
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``autoclobber`` describes the behavior that will occur if a
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database with the same name as the test database is discovered:
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* If ``autoclobber`` is ``False``, the user will be asked to
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approve destroying the existing database. ``sys.exit`` is
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called if the user does not approve.
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* If autoclobber is ``True``, the database will be destroyed
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without consulting the user.
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Returns the name of the test database that it created.
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``create_test_db()`` has the side effect of modifying the value of
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:setting:`NAME` in :setting:`DATABASES` to match the name of the test
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database.
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.. function:: destroy_test_db(old_database_name, [verbosity=1])
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Destroys the database whose name is the value of :setting:`NAME` in
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:setting:`DATABASES`, and sets :setting:`NAME` to the value of
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``old_database_name``.
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The ``verbosity`` argument has the same behavior as for
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:class:`~django.test.runner.DiscoverRunner`.
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.. _topics-testing-code-coverage:
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Integration with coverage.py
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============================
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Code coverage describes how much source code has been tested. It shows which
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parts of your code are being exercised by tests and which are not. It's an
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important part of testing applications, so it's strongly recommended to check
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the coverage of your tests.
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Django can be easily integrated with `coverage.py`_, a tool for measuring code
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coverage of Python programs. First, `install coverage.py`_. Next, run the
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following from your project folder containing ``manage.py``::
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coverage run --source='.' manage.py test myapp
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This runs your tests and collects coverage data of the executed files in your
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project. You can see a report of this data by typing following command::
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coverage report
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Note that some Django code was executed while running tests, but it is not
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listed here because of the ``source`` flag passed to the previous command.
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For more options like annotated HTML listings detailing missed lines, see the
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`coverage.py`_ docs.
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.. _coverage.py: http://nedbatchelder.com/code/coverage/
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.. _install coverage.py: http://pypi.python.org/pypi/coverage
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