Viewing github.com/django/django-stable-4.1.x/docs/topics/testing/tools.txt

```
=============
```
```
Testing tools
```
```
=============
```
```
.. currentmodule:: django.test
```

Django provides a small set of tools that come in handy when writing tests.

```
.. _test-client:
```
```
The test client
```
```
===============
```

The test client is a Python class that acts as a dummy web browser, allowing

you to test your views and interact with your Django-powered application

```
programmatically.
```

Some of the things you can do with the test client are:

* Simulate GET and POST requests on a URL and observe the response --

  everything from low-level HTTP (result headers and status codes) to

```
  page content.
```

* See the chain of redirects (if any) and check the URL and status code at

```
  each step.
```

* Test that a given request is rendered by a given Django template, with

  a template context that contains certain values.

Note that the test client is not intended to be a replacement for Selenium_ or

other "in-browser" frameworks. Django's test client has a different focus. In

```
short:
```

* Use Django's test client to establish that the correct template is being

  rendered and that the template is passed the correct context data.

* Use :class:`~django.test.RequestFactory` to test view functions directly,

  bypassing the routing and middleware layers.

* Use in-browser frameworks like Selenium_ to test *rendered* HTML and the

  *behavior* of web pages, namely JavaScript functionality. Django also

  provides special support for those frameworks; see the section on

  :class:`~django.test.LiveServerTestCase` for more details.

A comprehensive test suite should use a combination of all of these test types.

```
Overview and a quick example
```
```
----------------------------
```

To use the test client, instantiate ``django.test.Client`` and retrieve

```
web pages::
```
```
    >>> from django.test import Client
```
```
    >>> c = Client()
```

    >>> response = c.post('/login/', {'username': 'john', 'password': 'smith'})

```
    >>> response.status_code
```
```
    200
```

    >>> response = c.get('/customer/details/')

```
    >>> response.content
```
```
    b'<!DOCTYPE html...'
```

As this example suggests, you can instantiate ``Client`` from within a session

```
of the Python interactive interpreter.
```

Note a few important things about how the test client works:

* The test client does *not* require the web server to be running. In fact,

  it will run just fine with no web server running at all! That's because

  it avoids the overhead of HTTP and deals directly with the Django

  framework. This helps make the unit tests run quickly.

* When retrieving pages, remember to specify the *path* of the URL, not the

  whole domain. For example, this is correct::

```
      >>> c.get('/login/')
```
```
  This is incorrect::
```

      >>> c.get('https://www.example.com/login/')

  The test client is not capable of retrieving web pages that are not

  powered by your Django project. If you need to retrieve other web pages,

  use a Python standard library module such as :mod:`urllib`.

* To resolve URLs, the test client uses whatever URLconf is pointed-to by

  your :setting:`ROOT_URLCONF` setting.

* Although the above example would work in the Python interactive

  interpreter, some of the test client's functionality, notably the

  template-related functionality, is only available *while tests are

```
  running*.
```

  The reason for this is that Django's test runner performs a bit of black

  magic in order to determine which template was loaded by a given view.

  This black magic (essentially a patching of Django's template system in

  memory) only happens during test running.

* By default, the test client will disable any CSRF checks

```
  performed by your site.
```

  If, for some reason, you *want* the test client to perform CSRF

  checks, you can create an instance of the test client that

  enforces CSRF checks. To do this, pass in the

  ``enforce_csrf_checks`` argument when you construct your

```
  client::
```

      >>> from django.test import Client

      >>> csrf_client = Client(enforce_csrf_checks=True)

```
Making requests
```
```
---------------
```

Use the ``django.test.Client`` class to make requests.

.. class:: Client(enforce_csrf_checks=False, raise_request_exception=True, json_encoder=DjangoJSONEncoder, **defaults)

    It requires no arguments at time of construction. However, you can use

    keyword arguments to specify some default headers. For example, this will

    send a ``User-Agent`` HTTP header in each request::

        >>> c = Client(HTTP_USER_AGENT='Mozilla/5.0')

    The values from the ``extra`` keyword arguments passed to

```
    :meth:`~django.test.Client.get()`,
```

    :meth:`~django.test.Client.post()`, etc. have precedence over

    the defaults passed to the class constructor.

    The ``enforce_csrf_checks`` argument can be used to test CSRF

```
    protection (see above).
```

    The ``raise_request_exception`` argument allows controlling whether or not

    exceptions raised during the request should also be raised in the test.

```
    Defaults to ``True``.
```

    The ``json_encoder`` argument allows setting a custom JSON encoder for

    the JSON serialization that's described in :meth:`post`.

    Once you have a ``Client`` instance, you can call any of the following

```
    methods:
```

    .. method:: Client.get(path, data=None, follow=False, secure=False, **extra)

        Makes a GET request on the provided ``path`` and returns a ``Response``

        object, which is documented below.

        The key-value pairs in the ``data`` dictionary are used to create a GET

```
        data payload. For example::
```
```
            >>> c = Client()
```

            >>> c.get('/customers/details/', {'name': 'fred', 'age': 7})

        ...will result in the evaluation of a GET request equivalent to::

            /customers/details/?name=fred&age=7

        The ``extra`` keyword arguments parameter can be used to specify

        headers to be sent in the request. For example::

```
            >>> c = Client()
```

            >>> c.get('/customers/details/', {'name': 'fred', 'age': 7},

            ...       HTTP_ACCEPT='application/json')

        ...will send the HTTP header ``HTTP_ACCEPT`` to the details view, which

        is a good way to test code paths that use the

        :meth:`django.http.HttpRequest.accepts()` method.

        .. admonition:: CGI specification

            The headers sent via ``**extra`` should follow CGI_ specification.

            For example, emulating a different "Host" header as sent in the

            HTTP request from the browser to the server should be passed

```
            as ``HTTP_HOST``.
```

            .. _CGI: https://www.w3.org/CGI/

        If you already have the GET arguments in URL-encoded form, you can

        use that encoding instead of using the data argument. For example,

        the previous GET request could also be posed as::

```
        >>> c = Client()
```

        >>> c.get('/customers/details/?name=fred&age=7')

        If you provide a URL with both an encoded GET data and a data argument,

        the data argument will take precedence.

        If you set ``follow`` to ``True`` the client will follow any redirects

        and a ``redirect_chain`` attribute will be set in the response object

        containing tuples of the intermediate urls and status codes.

        If you had a URL ``/redirect_me/`` that redirected to ``/next/``, that

        redirected to ``/final/``, this is what you'd see::

            >>> response = c.get('/redirect_me/', follow=True)

            >>> response.redirect_chain

            [('http://testserver/next/', 302), ('http://testserver/final/', 302)]

        If you set ``secure`` to ``True`` the client will emulate an HTTPS

```
        request.
```

    .. method:: Client.post(path, data=None, content_type=MULTIPART_CONTENT, follow=False, secure=False, **extra)

        Makes a POST request on the provided ``path`` and returns a

        ``Response`` object, which is documented below.

        The key-value pairs in the ``data`` dictionary are used to submit POST

```
        data. For example::
```
```
            >>> c = Client()
```

            >>> c.post('/login/', {'name': 'fred', 'passwd': 'secret'})

        ...will result in the evaluation of a POST request to this URL::

```
            /login/
```
```
        ...with this POST data::
```
```
            name=fred&passwd=secret
```

        If you provide ``content_type`` as :mimetype:`application/json`, the

        ``data`` is serialized using :func:`json.dumps` if it's a dict, list,

        or tuple. Serialization is performed with

        :class:`~django.core.serializers.json.DjangoJSONEncoder` by default,

        and can be overridden by providing a ``json_encoder`` argument to

        :class:`Client`. This serialization also happens for :meth:`put`,

        :meth:`patch`, and :meth:`delete` requests.

        If you provide any other ``content_type`` (e.g. :mimetype:`text/xml`

        for an XML payload), the contents of ``data`` are sent as-is in the

        POST request, using ``content_type`` in the HTTP ``Content-Type``

```
        header.
```

        If you don't provide a value for ``content_type``, the values in

        ``data`` will be transmitted with a content type of

        :mimetype:`multipart/form-data`. In this case, the key-value pairs in

        ``data`` will be encoded as a multipart message and used to create the

```
        POST data payload.
```

        To submit multiple values for a given key -- for example, to specify

        the selections for a ``<select multiple>`` -- provide the values as a

        list or tuple for the required key. For example, this value of ``data``

        would submit three selected values for the field named ``choices``::

            {'choices': ('a', 'b', 'd')}

        Submitting files is a special case. To POST a file, you need only

        provide the file field name as a key, and a file handle to the file you

        wish to upload as a value. For example, if your form has fields

        ``name`` and ``attachment``, the latter a

        :class:`~django.forms.FileField`::

```
            >>> c = Client()
```

            >>> with open('wishlist.doc', 'rb') as fp:

            ...     c.post('/customers/wishes/', {'name': 'fred', 'attachment': fp})

        You may also provide any file-like object (e.g., :class:`~io.StringIO` or

        :class:`~io.BytesIO`) as a file handle. If you're uploading to an

        :class:`~django.db.models.ImageField`, the object needs a ``name``

```
        attribute that passes the
```

        :data:`~django.core.validators.validate_image_file_extension` validator.

```
        For example::
```
```
            >>> from io import BytesIO
```
```
            >>> img = BytesIO(
```

            ...     b"GIF89a\x01\x00\x01\x00\x00\x00\x00!\xf9\x04\x01\x00\x00\x00"

            ...     b"\x00,\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x01\x00\x00"

```
            ... )
```

            >>> img.name = "myimage.gif"

        Note that if you wish to use the same file handle for multiple

        ``post()`` calls then you will need to manually reset the file

        pointer between posts. The easiest way to do this is to

        manually close the file after it has been provided to

        ``post()``, as demonstrated above.

        You should also ensure that the file is opened in a way that

        allows the data to be read. If your file contains binary data

        such as an image, this means you will need to open the file in

```
        ``rb`` (read binary) mode.
```

        The ``extra`` argument acts the same as for :meth:`Client.get`.

        If the URL you request with a POST contains encoded parameters, these

        parameters will be made available in the request.GET data. For example,

        if you were to make the request::

        >>> c.post('/login/?visitor=true', {'name': 'fred', 'passwd': 'secret'})

        ... the view handling this request could interrogate request.POST

        to retrieve the username and password, and could interrogate request.GET

        to determine if the user was a visitor.

        If you set ``follow`` to ``True`` the client will follow any redirects

        and a ``redirect_chain`` attribute will be set in the response object

        containing tuples of the intermediate urls and status codes.

        If you set ``secure`` to ``True`` the client will emulate an HTTPS

```
        request.
```

    .. method:: Client.head(path, data=None, follow=False, secure=False, **extra)

        Makes a HEAD request on the provided ``path`` and returns a

        ``Response`` object. This method works just like :meth:`Client.get`,

        including the ``follow``, ``secure`` and ``extra`` arguments, except

        it does not return a message body.

    .. method:: Client.options(path, data='', content_type='application/octet-stream', follow=False, secure=False, **extra)

        Makes an OPTIONS request on the provided ``path`` and returns a

        ``Response`` object. Useful for testing RESTful interfaces.

        When ``data`` is provided, it is used as the request body, and

        a ``Content-Type`` header is set to ``content_type``.

        The ``follow``, ``secure`` and ``extra`` arguments act the same as for

```
        :meth:`Client.get`.
```

    .. method:: Client.put(path, data='', content_type='application/octet-stream', follow=False, secure=False, **extra)

        Makes a PUT request on the provided ``path`` and returns a

        ``Response`` object. Useful for testing RESTful interfaces.

        When ``data`` is provided, it is used as the request body, and

        a ``Content-Type`` header is set to ``content_type``.

        The ``follow``, ``secure`` and ``extra`` arguments act the same as for

```
        :meth:`Client.get`.
```

    .. method:: Client.patch(path, data='', content_type='application/octet-stream', follow=False, secure=False, **extra)

        Makes a PATCH request on the provided ``path`` and returns a

        ``Response`` object. Useful for testing RESTful interfaces.

        The ``follow``, ``secure`` and ``extra`` arguments act the same as for

```
        :meth:`Client.get`.
```

    .. method:: Client.delete(path, data='', content_type='application/octet-stream', follow=False, secure=False, **extra)

        Makes a DELETE request on the provided ``path`` and returns a

        ``Response`` object. Useful for testing RESTful interfaces.

        When ``data`` is provided, it is used as the request body, and

        a ``Content-Type`` header is set to ``content_type``.

        The ``follow``, ``secure`` and ``extra`` arguments act the same as for

```
        :meth:`Client.get`.
```

    .. method:: Client.trace(path, follow=False, secure=False, **extra)

        Makes a TRACE request on the provided ``path`` and returns a

        ``Response`` object. Useful for simulating diagnostic probes.

        Unlike the other request methods, ``data`` is not provided as a keyword

        parameter in order to comply with :rfc:`7231#section-4.3.8`, which

        mandates that TRACE requests must not have a body.

        The ``follow``, ``secure``, and ``extra`` arguments act the same as for

```
        :meth:`Client.get`.
```

    .. method:: Client.login(**credentials)

        If your site uses Django's :doc:`authentication system</topics/auth/index>`

        and you deal with logging in users, you can use the test client's

        ``login()`` method to simulate the effect of a user logging into the

```
        site.
```

        After you call this method, the test client will have all the cookies

        and session data required to pass any login-based tests that may form

```
        part of a view.
```

        The format of the ``credentials`` argument depends on which

        :ref:`authentication backend <authentication-backends>` you're using

        (which is configured by your :setting:`AUTHENTICATION_BACKENDS`

        setting). If you're using the standard authentication backend provided

        by Django (``ModelBackend``), ``credentials`` should be the user's

        username and password, provided as keyword arguments::

```
            >>> c = Client()
```

            >>> c.login(username='fred', password='secret')

            # Now you can access a view that's only available to logged-in users.

        If you're using a different authentication backend, this method may

        require different credentials. It requires whichever credentials are

        required by your backend's ``authenticate()`` method.

        ``login()`` returns ``True`` if it the credentials were accepted and

```
        login was successful.
```

        Finally, you'll need to remember to create user accounts before you can

        use this method. As we explained above, the test runner is executed

        using a test database, which contains no users by default. As a result,

        user accounts that are valid on your production site will not work

        under test conditions. You'll need to create users as part of the test

        suite -- either manually (using the Django model API) or with a test

        fixture. Remember that if you want your test user to have a password,

        you can't set the user's password by setting the password attribute

```
        directly -- you must use the
```

        :meth:`~django.contrib.auth.models.User.set_password()` function to

        store a correctly hashed password. Alternatively, you can use the

        :meth:`~django.contrib.auth.models.UserManager.create_user` helper

        method to create a new user with a correctly hashed password.

    .. method:: Client.force_login(user, backend=None)

        If your site uses Django's :doc:`authentication

        system</topics/auth/index>`, you can use the ``force_login()`` method

        to simulate the effect of a user logging into the site. Use this method

        instead of :meth:`login` when a test requires a user be logged in and

        the details of how a user logged in aren't important.

        Unlike ``login()``, this method skips the authentication and

        verification steps: inactive users (:attr:`is_active=False

        <django.contrib.auth.models.User.is_active>`) are permitted to login

        and the user's credentials don't need to be provided.

        The user will have its ``backend`` attribute set to the value of the

        ``backend`` argument (which should be a dotted Python path string), or

        to ``settings.AUTHENTICATION_BACKENDS[0]`` if a value isn't provided.

        The :func:`~django.contrib.auth.authenticate` function called by

        :meth:`login` normally annotates the user like this.

        This method is faster than ``login()`` since the expensive

        password hashing algorithms are bypassed. Also, you can speed up

        ``login()`` by :ref:`using a weaker hasher while testing

        <speeding-up-tests-auth-hashers>`.

```
    .. method:: Client.logout()
```

        If your site uses Django's :doc:`authentication system</topics/auth/index>`,

        the ``logout()`` method can be used to simulate the effect of a user

```
        logging out of your site.
```

        After you call this method, the test client will have all the cookies

        and session data cleared to defaults. Subsequent requests will appear

        to come from an :class:`~django.contrib.auth.models.AnonymousUser`.

```
Testing responses
```
```
-----------------
```

The ``get()`` and ``post()`` methods both return a ``Response`` object. This

``Response`` object is *not* the same as the ``HttpResponse`` object returned

by Django views; the test response object has some additional data useful for

```
test code to verify.
```

Specifically, a ``Response`` object has the following attributes:

```
.. class:: Response()
```
```
    .. attribute:: client
```

        The test client that was used to make the request that resulted in the

```
        response.
```
```
    .. attribute:: content
```

        The body of the response, as a bytestring. This is the final page

        content as rendered by the view, or any error message.

```
    .. attribute:: context
```

        The template ``Context`` instance that was used to render the template that

```
        produced the response content.
```

        If the rendered page used multiple templates, then ``context`` will be a

        list of ``Context`` objects, in the order in which they were rendered.

        Regardless of the number of templates used during rendering, you can

        retrieve context values using the ``[]`` operator. For example, the

        context variable ``name`` could be retrieved using::

            >>> response = client.get('/foo/')

            >>> response.context['name']

```
            'Arthur'
```

        .. admonition:: Not using Django templates?

            This attribute is only populated when using the

            :class:`~django.template.backends.django.DjangoTemplates` backend.

            If you're using another template engine,

            :attr:`~django.template.response.SimpleTemplateResponse.context_data`

            may be a suitable alternative on responses with that attribute.

```
    .. attribute:: exc_info
```

        A tuple of three values that provides information about the unhandled

        exception, if any, that occurred during the view.

        The values are (type, value, traceback), the same as returned by

        Python's :func:`sys.exc_info`. Their meanings are:

        - *type*: The type of the exception.

        - *value*: The exception instance.

        - *traceback*: A traceback object which encapsulates the call stack at

          the point where the exception originally occurred.

        If no exception occurred, then ``exc_info`` will be ``None``.

```
    .. method:: json(**kwargs)
```

        The body of the response, parsed as JSON. Extra keyword arguments are

        passed to :func:`json.loads`. For example::

            >>> response = client.get('/foo/')

            >>> response.json()['name']

```
            'Arthur'
```

        If the ``Content-Type`` header is not ``"application/json"``, then a

        :exc:`ValueError` will be raised when trying to parse the response.

```
    .. attribute:: request
```

        The request data that stimulated the response.

```
    .. attribute:: wsgi_request
```

        The ``WSGIRequest`` instance generated by the test handler that

```
        generated the response.
```
```
    .. attribute:: status_code
```

        The HTTP status of the response, as an integer. For a full list

        of defined codes, see the `IANA status code registry`_.

        .. _IANA status code registry: https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

```
    .. attribute:: templates
```

        A list of ``Template`` instances used to render the final content, in

        the order they were rendered. For each template in the list, use

        ``template.name`` to get the template's file name, if the template was

        loaded from a file. (The name is a string such as

```
        ``'admin/index.html'``.)
```

        .. admonition:: Not using Django templates?

            This attribute is only populated when using the

            :class:`~django.template.backends.django.DjangoTemplates` backend.

            If you're using another template engine,

            :attr:`~django.template.response.SimpleTemplateResponse.template_name`

            may be a suitable alternative if you only need the name of the

            template used for rendering.

```
    .. attribute:: resolver_match
```

        An instance of :class:`~django.urls.ResolverMatch` for the response.

        You can use the :attr:`~django.urls.ResolverMatch.func` attribute, for

        example, to verify the view that served the response::

            # my_view here is a function based view.

            self.assertEqual(response.resolver_match.func, my_view)

            # Class-based views need to compare the view_class, as the

            # functions generated by as_view() won't be equal.

            self.assertIs(response.resolver_match.func.view_class, MyView)

        If the given URL is not found, accessing this attribute will raise a

        :exc:`~django.urls.Resolver404` exception.

As with a normal response, you can also access the headers through

:attr:`.HttpResponse.headers`. For example, you could determine the content

type of a response using ``response.headers['Content-Type']``.

```
Exceptions
```
```
----------
```

If you point the test client at a view that raises an exception and

``Client.raise_request_exception`` is ``True``, that exception will be visible

in the test case. You can then use a standard ``try ... except`` block or

:meth:`~unittest.TestCase.assertRaises` to test for exceptions.

The only exceptions that are not visible to the test client are

```
:class:`~django.http.Http404`,
```

:class:`~django.core.exceptions.PermissionDenied`, :exc:`SystemExit`, and

:class:`~django.core.exceptions.SuspiciousOperation`. Django catches these

exceptions internally and converts them into the appropriate HTTP response

codes. In these cases, you can check ``response.status_code`` in your test.

If ``Client.raise_request_exception`` is ``False``, the test client will return a

500 response as would be returned to a browser. The response has the attribute

:attr:`~Response.exc_info` to provide information about the unhandled

```
exception.
```
```
Persistent state
```
```
----------------
```

The test client is stateful. If a response returns a cookie, then that cookie

will be stored in the test client and sent with all subsequent ``get()`` and

```
``post()`` requests.
```

Expiration policies for these cookies are not followed. If you want a cookie

to expire, either delete it manually or create a new ``Client`` instance (which

```
will effectively delete all cookies).
```

A test client has attributes that store persistent state information. You can

access these properties as part of a test condition.

```
.. attribute:: Client.cookies
```

    A Python :class:`~http.cookies.SimpleCookie` object, containing the current

    values of all the client cookies. See the documentation of the

    :mod:`http.cookies` module for more.

```
.. attribute:: Client.session
```

    A dictionary-like object containing session information. See the

    :doc:`session documentation</topics/http/sessions>` for full details.

    To modify the session and then save it, it must be stored in a variable

    first (because a new ``SessionStore`` is created every time this property

```
    is accessed)::
```
```
        def test_something(self):
```

            session = self.client.session

            session['somekey'] = 'test'

```
            session.save()
```
```
Setting the language
```
```
--------------------
```

When testing applications that support internationalization and localization,

you might want to set the language for a test client request. The method for

```
doing so depends on whether or not the
```

:class:`~django.middleware.locale.LocaleMiddleware` is enabled.

If the middleware is enabled, the language can be set by creating a cookie with

a name of :setting:`LANGUAGE_COOKIE_NAME` and a value of the language code::

```
    from django.conf import settings
```

    def test_language_using_cookie(self):

        self.client.cookies.load({settings.LANGUAGE_COOKIE_NAME: 'fr'})

        response = self.client.get('/')

        self.assertEqual(response.content, b"Bienvenue sur mon site.")

or by including the ``Accept-Language`` HTTP header in the request::

    def test_language_using_header(self):

        response = self.client.get('/', HTTP_ACCEPT_LANGUAGE='fr')

        self.assertEqual(response.content, b"Bienvenue sur mon site.")

```
.. note::
```

    When using these methods, ensure to reset the active language at the end of

```
    each test::
```
```
        def tearDown(self):
```

            translation.activate(settings.LANGUAGE_CODE)

More details are in :ref:`how-django-discovers-language-preference`.

If the middleware isn't enabled, the active language may be set using

```
:func:`.translation.override`::
```

    from django.utils import translation

    def test_language_using_override(self):

        with translation.override('fr'):

            response = self.client.get('/')

        self.assertEqual(response.content, b"Bienvenue sur mon site.")

More details are in :ref:`explicitly-setting-the-active-language`.

```
Example
```
```
-------
```

The following is a unit test using the test client::

```
    import unittest
```
```
    from django.test import Client
```

    class SimpleTest(unittest.TestCase):

```
        def setUp(self):
```

            # Every test needs a client.

```
            self.client = Client()
```
```
        def test_details(self):
```
```
            # Issue a GET request.
```

            response = self.client.get('/customer/details/')

            # Check that the response is 200 OK.

            self.assertEqual(response.status_code, 200)

            # Check that the rendered context contains 5 customers.

            self.assertEqual(len(response.context['customers']), 5)

```
.. seealso::
```

    :class:`django.test.RequestFactory`

```
.. _django-testcase-subclasses:
```
```
Provided test case classes
```
```
==========================
```

Normal Python unit test classes extend a base class of

:class:`unittest.TestCase`. Django provides a few extensions of this base class:

```
.. _testcase_hierarchy_diagram:
```

.. figure:: _images/django_unittest_classes_hierarchy.*

   :alt: Hierarchy of Django unit testing classes (TestCase subclasses)

```
   :width: 508
```
```
   :height: 328
```

   Hierarchy of Django unit testing classes

You can convert a normal :class:`unittest.TestCase` to any of the subclasses:

change the base class of your test from ``unittest.TestCase`` to the subclass.

All of the standard Python unit test functionality will be available, and it

will be augmented with some useful additions as described in each section

```
below.
```
```
``SimpleTestCase``
```
```
------------------
```
```
.. class:: SimpleTestCase()
```

A subclass of :class:`unittest.TestCase` that adds this functionality:

```
* Some useful assertions like:
```

  * Checking that a callable :meth:`raises a certain exception

    <SimpleTestCase.assertRaisesMessage>`.

  * Checking that a callable :meth:`triggers a certain warning

    <SimpleTestCase.assertWarnsMessage>`.

  * Testing form field :meth:`rendering and error treatment

    <SimpleTestCase.assertFieldOutput>`.

  * Testing :meth:`HTML responses for the presence/lack of a given fragment

```
    <SimpleTestCase.assertContains>`.
```

  * Verifying that a template :meth:`has/hasn't been used to generate a given

    response content <SimpleTestCase.assertTemplateUsed>`.

  * Verifying that two :meth:`URLs <SimpleTestCase.assertURLEqual>` are equal.

  * Verifying an HTTP :meth:`redirect <SimpleTestCase.assertRedirects>` is

```
    performed by the app.
```

  * Robustly testing two :meth:`HTML fragments <SimpleTestCase.assertHTMLEqual>`

    for equality/inequality or :meth:`containment <SimpleTestCase.assertInHTML>`.

  * Robustly testing two :meth:`XML fragments <SimpleTestCase.assertXMLEqual>`

```
    for equality/inequality.
```

  * Robustly testing two :meth:`JSON fragments <SimpleTestCase.assertJSONEqual>`

```
    for equality.
```

* The ability to run tests with :ref:`modified settings <overriding-settings>`.

* Using the :attr:`~SimpleTestCase.client` :class:`~django.test.Client`.

If your tests make any database queries, use subclasses

:class:`~django.test.TransactionTestCase` or :class:`~django.test.TestCase`.

.. attribute:: SimpleTestCase.databases

    :class:`~SimpleTestCase` disallows database queries by default. This

    helps to avoid executing write queries which will affect other tests

    since each ``SimpleTestCase`` test isn't run in a transaction. If you

    aren't concerned about this problem, you can disable this behavior by

    setting the ``databases`` class attribute to ``'__all__'`` on your test

```
    class.
```
```
.. warning::
```

    ``SimpleTestCase`` and its subclasses (e.g. ``TestCase``, ...) rely on

    ``setUpClass()`` and ``tearDownClass()`` to perform some class-wide

    initialization (e.g. overriding settings). If you need to override those

    methods, don't forget to call the ``super`` implementation::

```
        class MyTestCase(TestCase):
```
```
            @classmethod
```
```
            def setUpClass(cls):
```
```
                super().setUpClass()
```
```
                ...
```
```
            @classmethod
```
```
            def tearDownClass(cls):
```
```
                ...
```

                super().tearDownClass()

    Be sure to account for Python's behavior if an exception is raised during

    ``setUpClass()``. If that happens, neither the tests in the class nor

    ``tearDownClass()`` are run. In the case of :class:`django.test.TestCase`,

    this will leak the transaction created in ``super()``  which results in

    various symptoms including a segmentation fault on some platforms (reported

    on macOS). If you want to intentionally raise an exception such as

    :exc:`unittest.SkipTest` in ``setUpClass()``, be sure to do it before

```
    calling ``super()`` to avoid this.
```
```
``TransactionTestCase``
```
```
-----------------------
```
```
.. class:: TransactionTestCase()
```

``TransactionTestCase`` inherits from :class:`~django.test.SimpleTestCase` to

```
add some database-specific features:
```

* Resetting the database to a known state at the beginning of each test to

```
  ease testing and using the ORM.
```

* Database :attr:`~TransactionTestCase.fixtures`.

* Test :ref:`skipping based on database backend features <skipping-tests>`.

* The remaining specialized :meth:`assert*

  <TransactionTestCase.assertQuerysetEqual>` methods.

Django's :class:`TestCase` class is a more commonly used subclass of

``TransactionTestCase`` that makes use of database transaction facilities

to speed up the process of resetting the database to a known state at the

beginning of each test. A consequence of this, however, is that some database

behaviors cannot be tested within a Django ``TestCase`` class. For instance,

you cannot test that a block of code is executing within a transaction, as is

```
required when using
```

:meth:`~django.db.models.query.QuerySet.select_for_update()`. In those cases,

you should use ``TransactionTestCase``.

``TransactionTestCase`` and ``TestCase`` are identical except for the manner

in which the database is reset to a known state and the ability for test code

to test the effects of commit and rollback:

* A ``TransactionTestCase`` resets the database after the test runs by

  truncating all tables. A ``TransactionTestCase`` may call commit and rollback

  and observe the effects of these calls on the database.

* A ``TestCase``, on the other hand, does not truncate tables after a test.

  Instead, it encloses the test code in a database transaction that is rolled

  back at the end of the test. This guarantees that the rollback at the end of

  the test restores the database to its initial state.

```
.. warning::
```

  ``TestCase`` running on a database that does not support rollback (e.g. MySQL

  with the MyISAM storage engine), and all instances of ``TransactionTestCase``,

  will roll back at the end of the test by deleting all data from the test

```
  database.
```

  Apps :ref:`will not see their data reloaded <test-case-serialized-rollback>`;

  if you need this functionality (for example, third-party apps should enable

  this) you can set ``serialized_rollback = True`` inside the

```
  ``TestCase`` body.
```
```
``TestCase``
```
```
------------
```
```
.. class:: TestCase()
```

This is the most common class to use for writing tests in Django. It inherits

from :class:`TransactionTestCase` (and by extension :class:`SimpleTestCase`).

If your Django application doesn't use a database, use :class:`SimpleTestCase`.

```
The class:
```

* Wraps the tests within two nested :func:`~django.db.transaction.atomic`

  blocks: one for the whole class and one for each test. Therefore, if you want

  to test some specific database transaction behavior, use

```
  :class:`TransactionTestCase`.
```

* Checks deferrable database constraints at the end of each test.

```
It also provides an additional method:
```

.. classmethod:: TestCase.setUpTestData()

    The class-level ``atomic`` block described above allows the creation of

    initial data at the class level, once for the whole ``TestCase``. This

    technique allows for faster tests as compared to using ``setUp()``.

```
    For example::
```

        from django.test import TestCase

```
        class MyTests(TestCase):
```
```
            @classmethod
```
```
            def setUpTestData(cls):
```

                # Set up data for the whole TestCase

                cls.foo = Foo.objects.create(bar="Test")

```
                ...
```
```
            def test1(self):
```

                # Some test using self.foo

```
                ...
```
```
            def test2(self):
```

                # Some other test using self.foo

```
                ...
```

    Note that if the tests are run on a database with no transaction support

    (for instance, MySQL with the MyISAM engine), ``setUpTestData()`` will be

    called before each test, negating the speed benefits.

    Objects assigned to class attributes in ``setUpTestData()`` must support

    creating deep copies with :py:func:`copy.deepcopy` in order to isolate them

    from alterations performed by each test methods.

.. classmethod:: TestCase.captureOnCommitCallbacks(using=DEFAULT_DB_ALIAS, execute=False)

    Returns a context manager that captures :func:`transaction.on_commit()

    <django.db.transaction.on_commit>` callbacks for the given database

    connection. It returns a list that contains, on exit of the context, the

    captured callback functions. From this list you can make assertions on the

    callbacks or call them to invoke their side effects, emulating a commit.

    ``using`` is the alias of the database connection to capture callbacks for.

    If ``execute`` is ``True``, all the callbacks will be called as the context

    manager exits, if no exception occurred. This emulates a commit after the

```
    wrapped block of code.
```
```
    For example::
```
```
        from django.core import mail
```

        from django.test import TestCase

```
        class ContactTests(TestCase):
```
```
            def test_post(self):
```

                with self.captureOnCommitCallbacks(execute=True) as callbacks:

                    response = self.client.post(

```
                        '/contact/',
```

                        {'message': 'I like your site'},

```
                    )
```

                self.assertEqual(response.status_code, 200)

                self.assertEqual(len(callbacks), 1)

                self.assertEqual(len(mail.outbox), 1)

                self.assertEqual(mail.outbox[0].subject, 'Contact Form')

                self.assertEqual(mail.outbox[0].body, 'I like your site')

```
    .. versionchanged:: 4.0
```

        In older versions, new callbacks added while executing

        :func:`.transaction.on_commit` callbacks were not captured.

```
.. _live-test-server:
```
```
``LiveServerTestCase``
```
```
----------------------
```
```
.. class:: LiveServerTestCase()
```

``LiveServerTestCase`` does basically the same as

:class:`~django.test.TransactionTestCase` with one extra feature: it launches a

live Django server in the background on setup, and shuts it down on teardown.

This allows the use of automated test clients other than the

:ref:`Django dummy client <test-client>` such as, for example, the Selenium_

client, to execute a series of functional tests inside a browser and simulate a

```
real user's actions.
```

The live server listens on ``localhost`` and binds to port 0 which uses a free

port assigned by the operating system. The server's URL can be accessed with

``self.live_server_url`` during the tests.

To demonstrate how to use ``LiveServerTestCase``, let's write a Selenium test.

First of all, you need to install the `selenium package`_ into your Python

```
path:
```
```
.. console::
```
```
    $ python -m pip install selenium
```

Then, add a ``LiveServerTestCase``-based test to your app's tests module

(for example: ``myapp/tests.py``). For this example, we'll assume you're using

the :mod:`~django.contrib.staticfiles` app and want to have static files served

during the execution of your tests similar to what we get at development time

with ``DEBUG=True``, i.e. without having to collect them using

```
:djadmin:`collectstatic`. We'll use
```

the  :class:`~django.contrib.staticfiles.testing.StaticLiveServerTestCase`

subclass which provides that functionality. Replace it with

``django.test.LiveServerTestCase`` if you don't need that.

The code for this test may look as follows::

    from django.contrib.staticfiles.testing import StaticLiveServerTestCase

    from selenium.webdriver.common.by import By

    from selenium.webdriver.firefox.webdriver import WebDriver

    class MySeleniumTests(StaticLiveServerTestCase):

```
        fixtures = ['user-data.json']
```
```
        @classmethod
```
```
        def setUpClass(cls):
```
```
            super().setUpClass()
```
```
            cls.selenium = WebDriver()
```

            cls.selenium.implicitly_wait(10)

```
        @classmethod
```
```
        def tearDownClass(cls):
```
```
            cls.selenium.quit()
```
```
            super().tearDownClass()
```
```
        def test_login(self):
```

            self.selenium.get('%s%s' % (self.live_server_url, '/login/'))

            username_input = self.selenium.find_element(By.NAME, "username")

            username_input.send_keys('myuser')

            password_input = self.selenium.find_element(By.NAME, "password")

            password_input.send_keys('secret')

            self.selenium.find_element(By.XPATH, '//input[@value="Log in"]').click()

Finally, you may run the test as follows:

```
.. console::
```

    $ ./manage.py test myapp.tests.MySeleniumTests.test_login

This example will automatically open Firefox then go to the login page, enter

the credentials and press the "Log in" button. Selenium offers other drivers in

case you do not have Firefox installed or wish to use another browser. The

example above is just a tiny fraction of what the Selenium client can do; check

out the `full reference`_ for more details.

.. _Selenium: https://www.selenium.dev/

.. _selenium package: https://pypi.org/project/selenium/

.. _full reference: https://selenium-python.readthedocs.io/api.html

.. _Firefox: https://www.mozilla.com/firefox/

```
.. note::
```

    When using an in-memory SQLite database to run the tests, the same database

    connection will be shared by two threads in parallel: the thread in which

    the live server is run and the thread in which the test case is run. It's

    important to prevent simultaneous database queries via this shared

    connection by the two threads, as that may sometimes randomly cause the

    tests to fail. So you need to ensure that the two threads don't access the

    database at the same time. In particular, this means that in some cases

    (for example, just after clicking a link or submitting a form), you might

    need to check that a response is received by Selenium and that the next

    page is loaded before proceeding with further test execution.

    Do this, for example, by making Selenium wait until the ``<body>`` HTML tag

    is found in the response (requires Selenium > 2.13)::

```
        def test_login(self):
```

            from selenium.webdriver.support.wait import WebDriverWait

```
            timeout = 2
```
```
            ...
```

            self.selenium.find_element(By.XPATH, '//input[@value="Log in"]').click()

            # Wait until the response is received

            WebDriverWait(self.selenium, timeout).until(

                lambda driver: driver.find_element(By.TAG_NAME, 'body'))

    The tricky thing here is that there's really no such thing as a "page load,"

    especially in modern web apps that generate HTML dynamically after the

    server generates the initial document. So, checking for the presence of

    ``<body>`` in the response might not necessarily be appropriate for all use

    cases. Please refer to the `Selenium FAQ`_ and `Selenium documentation`_

```
    for more information.
```

    .. _Selenium FAQ: https://web.archive.org/web/20160129132110/http://code.google.com/p/selenium/wiki/FrequentlyAskedQuestions#Q:_WebDriver_fails_to_find_elements_/_Does_not_block_on_page_loa

    .. _Selenium documentation: https://www.selenium.dev/documentation/webdriver/waits/#explicit-wait

```
Test cases features
```
```
===================
```
```
Default test client
```
```
-------------------
```
```
.. attribute:: SimpleTestCase.client
```

Every test case in a ``django.test.*TestCase`` instance has access to an

instance of a Django test client. This client can be accessed as

``self.client``. This client is recreated for each test, so you don't have to

worry about state (such as cookies) carrying over from one test to another.

This means, instead of instantiating a ``Client`` in each test::

```
    import unittest
```
```
    from django.test import Client
```

    class SimpleTest(unittest.TestCase):

```
        def test_details(self):
```
```
            client = Client()
```

            response = client.get('/customer/details/')

            self.assertEqual(response.status_code, 200)

```
        def test_index(self):
```
```
            client = Client()
```

            response = client.get('/customer/index/')

            self.assertEqual(response.status_code, 200)

...you can refer to ``self.client``, like so::

```
    from django.test import TestCase
```
```
    class SimpleTest(TestCase):
```
```
        def test_details(self):
```

            response = self.client.get('/customer/details/')

            self.assertEqual(response.status_code, 200)

```
        def test_index(self):
```

            response = self.client.get('/customer/index/')

            self.assertEqual(response.status_code, 200)

```
Customizing the test client
```
```
---------------------------
```

.. attribute:: SimpleTestCase.client_class

If you want to use a different ``Client`` class (for example, a subclass

with customized behavior), use the :attr:`~SimpleTestCase.client_class` class

```
attribute::
```

    from django.test import Client, TestCase

```
    class MyTestClient(Client):
```

        # Specialized methods for your environment

```
        ...
```
```
    class MyTest(TestCase):
```
```
        client_class = MyTestClient
```
```
        def test_my_stuff(self):
```

            # Here self.client is an instance of MyTestClient...

```
            call_some_test_code()
```
```
.. _topics-testing-fixtures:
```
```
Fixture loading
```
```
---------------
```

.. attribute:: TransactionTestCase.fixtures

A test case for a database-backed website isn't much use if there isn't any

data in the database. Tests are more readable and it's more maintainable to

create objects using the ORM, for example in :meth:`TestCase.setUpTestData`,

```
however, you can also use fixtures.
```

A fixture is a collection of data that Django knows how to import into a

database. For example, if your site has user accounts, you might set up a

fixture of fake user accounts in order to populate your database during tests.

The most straightforward way of creating a fixture is to use the

:djadmin:`manage.py dumpdata <dumpdata>` command. This assumes you

already have some data in your database. See the :djadmin:`dumpdata

documentation<dumpdata>` for more details.

Once you've created a fixture and placed it in a ``fixtures`` directory in one

of your :setting:`INSTALLED_APPS`, you can use it in your unit tests by

specifying a ``fixtures`` class attribute on your :class:`django.test.TestCase`

```
subclass::
```
```
    from django.test import TestCase
```
```
    from myapp.models import Animal
```
```
    class AnimalTestCase(TestCase):
```

        fixtures = ['mammals.json', 'birds']

```
        def setUp(self):
```

            # Test definitions as before.

```
            call_setup_methods()
```
```
        def test_fluffy_animals(self):
```

            # A test that uses the fixtures.

```
            call_some_test_code()
```
```
Here's specifically what will happen:
```

* At the start of each test, before ``setUp()`` is run, Django will flush the

  database, returning the database to the state it was in directly after

```
  :djadmin:`migrate` was called.
```

* Then, all the named fixtures are installed. In this example, Django will

  install any JSON fixture named ``mammals``, followed by any fixture named

  ``birds``. See the :djadmin:`loaddata` documentation for more

  details on defining and installing fixtures.

For performance reasons, :class:`TestCase` loads fixtures once for the entire

test class, before :meth:`~TestCase.setUpTestData`, instead of before each

test, and it uses transactions to clean the database before each test. In any case,

you can be certain that the outcome of a test will not be affected by another

test or by the order of test execution.

By default, fixtures are only loaded into the ``default`` database. If you are

using multiple databases and set :attr:`TransactionTestCase.databases`,

fixtures will be loaded into all specified databases.

```
URLconf configuration
```
```
---------------------
```

If your application provides views, you may want to include tests that use the

test client to exercise those views. However, an end user is free to deploy the

views in your application at any URL of their choosing. This means that your

tests can't rely upon the fact that your views will be available at a

particular URL. Decorate your test class or test method with

``@override_settings(ROOT_URLCONF=...)`` for URLconf configuration.

```
.. _testing-multi-db:
```
```
Multi-database support
```
```
----------------------
```

.. attribute:: TransactionTestCase.databases

Django sets up a test database corresponding to every database that is

defined in the :setting:`DATABASES` definition in your settings and referred to

by at least one test through ``databases``.

However, a big part of the time taken to run a Django ``TestCase`` is consumed

by the call to ``flush`` that ensures that you have a clean database at the

start of each test run. If you have multiple databases, multiple flushes are

required (one for each database), which can be a time consuming activity --

especially if your tests don't need to test multi-database activity.

As an optimization, Django only flushes the ``default`` database at

the start of each test run. If your setup contains multiple databases,

and you have a test that requires every database to be clean, you can

use the ``databases`` attribute on the test suite to request extra databases

```
to be flushed.
```
```
For example::
```

    class TestMyViews(TransactionTestCase):

        databases = {'default', 'other'}

        def test_index_page_view(self):

```
            call_some_test_code()
```

This test case will flush the ``default`` and ``other`` test databases before

running ``test_index_page_view``. You can also use ``'__all__'`` to specify

that all of the test databases must be flushed.

The ``databases`` flag also controls which databases the

:attr:`TransactionTestCase.fixtures` are loaded into. By default, fixtures are

only loaded into the ``default`` database.

Queries against databases not in ``databases`` will give assertion errors to

```
prevent state leaking between tests.
```
```
.. attribute:: TestCase.databases
```

By default, only the ``default`` database will be wrapped in a transaction

during a ``TestCase``'s execution and attempts to query other databases will

result in assertion errors to prevent state leaking between tests.

Use the ``databases`` class attribute on the test class to request transaction

wrapping against non-``default`` databases.

```
For example::
```
```
    class OtherDBTests(TestCase):
```
```
        databases = {'other'}
```
```
        def test_other_db_query(self):
```
```
            ...
```

This test will only allow queries against the ``other`` database. Just like for

:attr:`SimpleTestCase.databases` and :attr:`TransactionTestCase.databases`, the

``'__all__'`` constant can be used to specify that the test should allow

```
queries to all databases.
```
```
.. _overriding-settings:
```
```
Overriding settings
```
```
-------------------
```
```
.. warning::
```

    Use the functions below to temporarily alter the value of settings in tests.

    Don't manipulate ``django.conf.settings`` directly as Django won't restore

    the original values after such manipulations.

```
.. method:: SimpleTestCase.settings()
```

For testing purposes it's often useful to change a setting temporarily and

revert to the original value after running the testing code. For this use case

Django provides a standard Python context manager (see :pep:`343`) called

:meth:`~django.test.SimpleTestCase.settings`, which can be used like this::

```
    from django.test import TestCase
```
```
    class LoginTestCase(TestCase):
```
```
        def test_login(self):
```

            # First check for the default behavior

            response = self.client.get('/sekrit/')

            self.assertRedirects(response, '/accounts/login/?next=/sekrit/')

            # Then override the LOGIN_URL setting

            with self.settings(LOGIN_URL='/other/login/'):

                response = self.client.get('/sekrit/')

                self.assertRedirects(response, '/other/login/?next=/sekrit/')

This example will override the :setting:`LOGIN_URL` setting for the code

in the ``with`` block and reset its value to the previous state afterward.

.. method:: SimpleTestCase.modify_settings()

It can prove unwieldy to redefine settings that contain a list of values. In

practice, adding or removing values is often sufficient. Django provides the

:meth:`~django.test.SimpleTestCase.modify_settings` context manager for easier

```
settings changes::
```
```
    from django.test import TestCase
```

    class MiddlewareTestCase(TestCase):

        def test_cache_middleware(self):

            with self.modify_settings(MIDDLEWARE={

                'append': 'django.middleware.cache.FetchFromCacheMiddleware',

                'prepend': 'django.middleware.cache.UpdateCacheMiddleware',

```
                'remove': [
```

                    'django.contrib.sessions.middleware.SessionMiddleware',

                    'django.contrib.auth.middleware.AuthenticationMiddleware',

                    'django.contrib.messages.middleware.MessageMiddleware',

```
                ],
```
```
            }):
```

                response = self.client.get('/')

```
                # ...
```

For each action, you can supply either a list of values or a string. When the

value already exists in the list, ``append`` and ``prepend`` have no effect;

neither does ``remove`` when the value doesn't exist.

.. function:: override_settings(**kwargs)

In case you want to override a setting for a test method, Django provides the

:func:`~django.test.override_settings` decorator (see :pep:`318`). It's used

```
like this::
```

    from django.test import TestCase, override_settings

```
    class LoginTestCase(TestCase):
```

        @override_settings(LOGIN_URL='/other/login/')

```
        def test_login(self):
```

            response = self.client.get('/sekrit/')

            self.assertRedirects(response, '/other/login/?next=/sekrit/')

The decorator can also be applied to :class:`~django.test.TestCase` classes::

    from django.test import TestCase, override_settings

    @override_settings(LOGIN_URL='/other/login/')

```
    class LoginTestCase(TestCase):
```
```
        def test_login(self):
```

            response = self.client.get('/sekrit/')

            self.assertRedirects(response, '/other/login/?next=/sekrit/')

.. function:: modify_settings(*args, **kwargs)

Likewise, Django provides the :func:`~django.test.modify_settings`

```
decorator::
```

    from django.test import TestCase, modify_settings

    class MiddlewareTestCase(TestCase):

```
        @modify_settings(MIDDLEWARE={
```

            'append': 'django.middleware.cache.FetchFromCacheMiddleware',

            'prepend': 'django.middleware.cache.UpdateCacheMiddleware',

```
        })
```

        def test_cache_middleware(self):

            response = self.client.get('/')

```
            # ...
```

The decorator can also be applied to test case classes::

    from django.test import TestCase, modify_settings

```
    @modify_settings(MIDDLEWARE={
```

        'append': 'django.middleware.cache.FetchFromCacheMiddleware',

        'prepend': 'django.middleware.cache.UpdateCacheMiddleware',

```
    })
```

    class MiddlewareTestCase(TestCase):

        def test_cache_middleware(self):

            response = self.client.get('/')

```
            # ...
```
```
.. note::
```

    When given a class, these decorators modify the class directly and return

    it; they don't create and return a modified copy of it. So if you try to

    tweak the above examples to assign the return value to a different name

    than ``LoginTestCase`` or ``MiddlewareTestCase``, you may be surprised to

    find that the original test case classes are still equally affected by the

    decorator. For a given class, :func:`~django.test.modify_settings` is

    always applied after :func:`~django.test.override_settings`.

```
.. warning::
```

    The settings file contains some settings that are only consulted during

    initialization of Django internals. If you change them with

    ``override_settings``, the setting is changed if you access it via the

    ``django.conf.settings`` module, however, Django's internals access it

    differently. Effectively, using :func:`~django.test.override_settings` or

    :func:`~django.test.modify_settings` with these settings is probably not

    going to do what you expect it to do.

    We do not recommend altering the :setting:`DATABASES` setting. Altering

    the :setting:`CACHES` setting is possible, but a bit tricky if you are

    using internals that make using of caching, like

    :mod:`django.contrib.sessions`. For example, you will have to reinitialize

    the session backend in a test that uses cached sessions and overrides

```
    :setting:`CACHES`.
```

    Finally, avoid aliasing your settings as module-level constants as

    ``override_settings()`` won't work on such values since they are

    only evaluated the first time the module is imported.

You can also simulate the absence of a setting by deleting it after settings

```
have been overridden, like this::
```
```
    @override_settings()
```
```
    def test_something(self):
```
```
        del settings.LOGIN_URL
```
```
        ...
```

When overriding settings, make sure to handle the cases in which your app's

code uses a cache or similar feature that retains state even if the setting is

changed. Django provides the :data:`django.test.signals.setting_changed`

signal that lets you register callbacks to clean up and otherwise reset state

```
when settings are changed.
```

Django itself uses this signal to reset various data:

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

Overridden settings              Data reset

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

USE_TZ, TIME_ZONE                Databases timezone

TEMPLATES                        Template engines

SERIALIZATION_MODULES            Serializers cache

LOCALE_PATHS, LANGUAGE_CODE      Default translation and loaded translations

MEDIA_ROOT, DEFAULT_FILE_STORAGE Default file storage

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

```
Isolating apps
```
```
--------------
```

.. function:: utils.isolate_apps(*app_labels, attr_name=None, kwarg_name=None)

    Registers the models defined within a wrapped context into their own

    isolated :attr:`~django.apps.apps` registry. This functionality is useful

    when creating model classes for tests, as the classes will be cleanly

    deleted afterward, and there is no risk of name collisions.

    The app labels which the isolated registry should contain must be passed as

    individual arguments. You can use ``isolate_apps()`` as a decorator or a

```
    context manager. For example::
```
```
        from django.db import models
```

        from django.test import SimpleTestCase

        from django.test.utils import isolate_apps

        class MyModelTests(SimpleTestCase):

```
            @isolate_apps("app_label")
```

            def test_model_definition(self):

                class TestModel(models.Model):

```
                    pass
```
```
                ...
```
```
    … or::
```

        with isolate_apps("app_label"):

            class TestModel(models.Model):

```
                pass
```
```
            ...
```

    The decorator form can also be applied to classes.

    Two optional keyword arguments can be specified:

    * ``attr_name``: attribute assigned the isolated registry if used as a

```
      class decorator.
```

    * ``kwarg_name``: keyword argument passing the isolated registry if used as

```
      a function decorator.
```

    The temporary ``Apps`` instance used to isolate model registration can be

    retrieved as an attribute when used as a class decorator by using the

```
    ``attr_name`` parameter::
```

        @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 alternatively as an argument on the test method when used as a method

    decorator by using the ``kwarg_name`` parameter::

        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)

```
.. _emptying-test-outbox:
```
```
Emptying the test outbox
```
```
------------------------
```

If you use any of Django's custom ``TestCase`` classes, the test runner will

clear the contents of the test email outbox at the start of each test case.

For more detail on email services during tests, see `Email services`_ below.

```
.. _assertions:
```
```
Assertions
```
```
----------
```

As Python's normal :class:`unittest.TestCase` class implements assertion methods

such as :meth:`~unittest.TestCase.assertTrue` and

:meth:`~unittest.TestCase.assertEqual`, Django's custom :class:`TestCase` class

provides a number of custom assertion methods that are useful for testing web

```
applications:
```

The failure messages given by most of these assertion methods can be customized

with the ``msg_prefix`` argument. This string will be prefixed to any failure

message generated by the assertion. This allows you to provide additional

details that may help you to identify the location and cause of a failure in

```
your test suite.
```

.. method:: SimpleTestCase.assertRaisesMessage(expected_exception, expected_message, callable, *args, **kwargs)

            SimpleTestCase.assertRaisesMessage(expected_exception, expected_message)

    Asserts that execution of ``callable`` raises ``expected_exception`` and

    that ``expected_message`` is found in the exception's message. Any other

    outcome is reported as a failure. It's a simpler version of

    :meth:`unittest.TestCase.assertRaisesRegex` with the difference that

    ``expected_message`` isn't treated as a regular expression.

    If only the ``expected_exception`` and ``expected_message`` parameters are

    given, returns a context manager so that the code being tested can be

    written inline rather than as a function::

        with self.assertRaisesMessage(ValueError, 'invalid literal for int()'):

```
            int('a')
```

.. method:: SimpleTestCase.assertWarnsMessage(expected_warning, expected_message, callable, *args, **kwargs)

            SimpleTestCase.assertWarnsMessage(expected_warning, expected_message)

    Analogous to :meth:`SimpleTestCase.assertRaisesMessage` but for

    :meth:`~unittest.TestCase.assertWarnsRegex` instead of

    :meth:`~unittest.TestCase.assertRaisesRegex`.

.. method:: SimpleTestCase.assertFieldOutput(fieldclass, valid, invalid, field_args=None, field_kwargs=None, empty_value='')

    Asserts that a form field behaves correctly with various inputs.

    :param fieldclass: the class of the field to be tested.

    :param valid: a dictionary mapping valid inputs to their expected cleaned

```
        values.
```

    :param invalid: a dictionary mapping invalid inputs to one or more raised

```
        error messages.
```

    :param field_args: the args passed to instantiate the field.

    :param field_kwargs: the kwargs passed to instantiate the field.

    :param empty_value: the expected clean output for inputs in ``empty_values``.

    For example, the following code tests that an ``EmailField`` accepts

    ``[email protected]`` as a valid email address, but rejects ``aaa`` with a reasonable

```
    error message::
```

        self.assertFieldOutput(EmailField, {'[email protected]': '[email protected]'}, {'aaa': ['Enter a valid email address.']})

.. method:: SimpleTestCase.assertFormError(form, field, errors, msg_prefix='')

    Asserts that a field on a form raises the provided list of errors.

    ``form`` is a ``Form`` instance. The form must be

    :ref:`bound <ref-forms-api-bound-unbound>` but not necessarily

    validated (``assertFormError()`` will automatically call ``full_clean()``

```
    on the form).
```

    ``field`` is the name of the field on the form to check. To check the form's

    :meth:`non-field errors <django.forms.Form.non_field_errors>`, use

```
    ``field=None``.
```

    ``errors`` is a list of all the error strings that the field is expected to

    have. You can also pass a single error string if you only expect one error

    which means that ``errors='error message'`` is the same as

```
    ``errors=['error message']``.
```
```
    .. versionchanged:: 4.1
```

        In older versions, using an empty error list with ``assertFormError()``

        would always pass, regardless of whether the field had any errors or

        not. Starting from Django 4.1, using ``errors=[]`` will only pass if

        the field actually has no errors.

        Django 4.1 also changed the behavior of ``assertFormError()`` when a

        field has multiple errors. In older versions, if a field had multiple

        errors and you checked for only some of them, the test would pass.

        Starting from Django 4.1, the error list must be an exact match to the

```
        field's actual errors.
```
```
    .. deprecated:: 4.1
```

        Support for passing a response object and a form name to

        ``assertFormError()`` is deprecated and will be removed in Django 5.0.

        Use the form instance directly instead.

.. method:: SimpleTestCase.assertFormsetError(formset, form_index, field, errors, msg_prefix='')

    Asserts that the ``formset`` raises the provided list of errors when

```
    rendered.
```

    ``formset`` is a ``Formset`` instance. The formset must be bound but not

    necessarily validated (``assertFormsetError()`` will automatically call the

```
    ``full_clean()`` on the formset).
```

    ``form_index`` is the number of the form within the ``Formset`` (starting

    from 0). Use ``form_index=None`` to check the formset's non-form errors,

    i.e. the errors you get when calling ``formset.non_form_errors()``. In that

    case you must also use ``field=None``.

    ``field`` and ``errors`` have the same meaning as the parameters to

```
    ``assertFormError()``.
```
```
    .. deprecated:: 4.1
```

        Support for passing a response object and a formset name to

        ``assertFormsetError()`` is deprecated and will be removed in Django

        5.0. Use the formset instance directly instead.

.. method:: SimpleTestCase.assertContains(response, text, count=None, status_code=200, msg_prefix='', html=False)

    Asserts that a :class:`response <django.http.HttpResponse>` produced the

    given :attr:`~django.http.HttpResponse.status_code` and that ``text``

    appears in its :attr:`~django.http.HttpResponse.content`. If ``count``

    is provided, ``text`` must occur exactly ``count`` times in the response.

    Set ``html`` to ``True`` to handle ``text`` as HTML. The comparison with

    the response content will be based on HTML semantics instead of

    character-by-character equality. Whitespace is ignored in most cases,

    attribute ordering is not significant. See

    :meth:`~SimpleTestCase.assertHTMLEqual` for more details.

.. method:: SimpleTestCase.assertNotContains(response, text, status_code=200, msg_prefix='', html=False)

    Asserts that a :class:`response <django.http.HttpResponse>` produced the

    given :attr:`~django.http.HttpResponse.status_code` and that ``text`` does

    *not* appear in its :attr:`~django.http.HttpResponse.content`.

    Set ``html`` to ``True`` to handle ``text`` as HTML. The comparison with

    the response content will be based on HTML semantics instead of

    character-by-character equality. Whitespace is ignored in most cases,

    attribute ordering is not significant. See

    :meth:`~SimpleTestCase.assertHTMLEqual` for more details.

.. method:: SimpleTestCase.assertTemplateUsed(response, template_name, msg_prefix='', count=None)

    Asserts that the template with the given name was used in rendering the

```
    response.
```

    ``response`` must be a response instance returned by the

    :class:`test client <django.test.Response>`.

    ``template_name`` should be a string such as ``'admin/index.html'``.

    The ``count`` argument is an integer indicating the number of times the

    template should be rendered. Default is ``None``, meaning that the template

    should be rendered one or more times.

    You can use this as a context manager, like this::

        with self.assertTemplateUsed('index.html'):

            render_to_string('index.html')

        with self.assertTemplateUsed(template_name='index.html'):

            render_to_string('index.html')

.. method:: SimpleTestCase.assertTemplateNotUsed(response, template_name, msg_prefix='')

    Asserts that the template with the given name was *not* used in rendering

```
    the response.
```

    You can use this as a context manager in the same way as

    :meth:`~SimpleTestCase.assertTemplateUsed`.

.. method:: SimpleTestCase.assertURLEqual(url1, url2, msg_prefix='')

    Asserts that two URLs are the same, ignoring the order of query string

    parameters except for parameters with the same name. For example,

    ``/path/?x=1&y=2`` is equal to ``/path/?y=2&x=1``, but

    ``/path/?a=1&a=2`` isn't equal to ``/path/?a=2&a=1``.

.. method:: SimpleTestCase.assertRedirects(response, expected_url, status_code=302, target_status_code=200, msg_prefix='', fetch_redirect_response=True)

    Asserts that the :class:`response <django.http.HttpResponse>` returned a

    :attr:`~django.http.HttpResponse.status_code` redirect status, redirected

    to ``expected_url`` (including any ``GET`` data), and that the final page

    was received with ``target_status_code``.

    If your request used the ``follow`` argument, the ``expected_url`` and

    ``target_status_code`` will be the url and status code for the final

```
    point of the redirect chain.
```

    If ``fetch_redirect_response`` is ``False``, the final page won't be

    loaded. Since the test client can't fetch external URLs, this is

    particularly useful if ``expected_url`` isn't part of your Django app.

    Scheme is handled correctly when making comparisons between two URLs. If

    there isn't any scheme specified in the location where we are redirected to,

    the original request's scheme is used. If present, the scheme in

    ``expected_url`` is the one used to make the comparisons to.

.. method:: SimpleTestCase.assertHTMLEqual(html1, html2, msg=None)

    Asserts that the strings ``html1`` and ``html2`` are equal. The comparison

    is based on HTML semantics. The comparison takes following things into

```
    account:
```

    * Whitespace before and after HTML tags is ignored.

    * All types of whitespace are considered equivalent.

    * All open tags are closed implicitly, e.g. when a surrounding tag is

      closed or the HTML document ends.

    * Empty tags are equivalent to their self-closing version.

    * The ordering of attributes of an HTML element is not significant.

    * Boolean attributes (like ``checked``) without an argument are equal to

      attributes that equal in name and value (see the examples).

    * Text, character references, and entity references that refer to the same

```
      character are equivalent.
```

    The following examples are valid tests and don't raise any

```
    ``AssertionError``::
```
```
        self.assertHTMLEqual(
```

            '<p>Hello <b>&#x27;world&#x27;!</p>',

```
            '''<p>
```

                Hello   <b>&#39;world&#39;! </b>

```
            </p>'''
```
```
        )
```
```
        self.assertHTMLEqual(
```

            '<input type="checkbox" checked="checked" id="id_accept_terms" />',

            '<input id="id_accept_terms" type="checkbox" checked>'

```
        )
```

    ``html1`` and ``html2`` must contain HTML. An ``AssertionError`` will be

    raised if one of them cannot be parsed.

    Output in case of error can be customized with the ``msg`` argument.

```
    .. versionchanged:: 4.0
```

        In older versions, any attribute (not only boolean attributes) without

        a value was considered equal to an attribute with the same name and

```
        value.
```

.. method:: SimpleTestCase.assertHTMLNotEqual(html1, html2, msg=None)

    Asserts that the strings ``html1`` and ``html2`` are *not* equal. The

    comparison is based on HTML semantics. See

    :meth:`~SimpleTestCase.assertHTMLEqual` for details.

    ``html1`` and ``html2`` must contain HTML. An ``AssertionError`` will be

    raised if one of them cannot be parsed.

    Output in case of error can be customized with the ``msg`` argument.

.. method:: SimpleTestCase.assertXMLEqual(xml1, xml2, msg=None)

    Asserts that the strings ``xml1`` and ``xml2`` are equal. The

    comparison is based on XML semantics. Similarly to

    :meth:`~SimpleTestCase.assertHTMLEqual`, the comparison is

    made on parsed content, hence only semantic differences are considered, not

    syntax differences. When invalid XML is passed in any parameter, an

    ``AssertionError`` is always raised, even if both strings are identical.

    XML declaration, document type, processing instructions, and comments are

    ignored. Only the root element and its children are compared.

    Output in case of error can be customized with the ``msg`` argument.

.. method:: SimpleTestCase.assertXMLNotEqual(xml1, xml2, msg=None)

    Asserts that the strings ``xml1`` and ``xml2`` are *not* equal. The

    comparison is based on XML semantics. See

    :meth:`~SimpleTestCase.assertXMLEqual` for details.

    Output in case of error can be customized with the ``msg`` argument.

.. method:: SimpleTestCase.assertInHTML(needle, haystack, count=None, msg_prefix='')

    Asserts that the HTML fragment ``needle`` is contained in the ``haystack``

```
    once.
```

    If the ``count`` integer argument is specified, then additionally the number

    of ``needle`` occurrences will be strictly verified.

    Whitespace in most cases is ignored, and attribute ordering is not

    significant. See :meth:`~SimpleTestCase.assertHTMLEqual` for more details.

.. method:: SimpleTestCase.assertJSONEqual(raw, expected_data, msg=None)

    Asserts that the JSON fragments ``raw`` and ``expected_data`` are equal.

    Usual JSON non-significant whitespace rules apply as the heavyweight is

    delegated to the :mod:`json` library.

    Output in case of error can be customized with the ``msg`` argument.

.. method:: SimpleTestCase.assertJSONNotEqual(raw, expected_data, msg=None)

    Asserts that the JSON fragments ``raw`` and ``expected_data`` are *not* equal.

    See :meth:`~SimpleTestCase.assertJSONEqual` for further details.

    Output in case of error can be customized with the ``msg`` argument.

.. method:: TransactionTestCase.assertQuerysetEqual(qs, values, transform=None, ordered=True, msg=None)

    Asserts that a queryset ``qs`` matches a particular iterable of values

```
    ``values``.
```

    If ``transform`` is provided, ``values`` is compared to a list produced by

    applying ``transform`` to each member of ``qs``.

    By default, the comparison is also ordering dependent. If ``qs`` doesn't

    provide an implicit ordering, you can set the ``ordered`` parameter to

    ``False``, which turns the comparison into a ``collections.Counter`` comparison.

    If the order is undefined (if the given ``qs`` isn't ordered and the

    comparison is against more than one ordered value), a ``ValueError`` is

```
    raised.
```

    Output in case of error can be customized with the ``msg`` argument.

.. method:: TransactionTestCase.assertNumQueries(num, func, *args, **kwargs)

    Asserts that when ``func`` is called with ``*args`` and ``**kwargs`` that

    ``num`` database queries are executed.

    If a ``"using"`` key is present in ``kwargs`` it is used as the database

    alias for which to check the number of queries::

        self.assertNumQueries(7, using='non_default_db')

    If you wish to call a function with a ``using`` parameter you can do it by

    wrapping the call with a ``lambda`` to add an extra parameter::

        self.assertNumQueries(7, lambda: my_function(using=7))

    You can also use this as a context manager::

```
        with self.assertNumQueries(2):
```

            Person.objects.create(name="Aaron")

            Person.objects.create(name="Daniel")

```
.. _topics-tagging-tests:
```
```
Tagging tests
```
```
-------------
```

You can tag your tests so you can easily run a particular subset. For example,

```
you might label fast or slow tests::
```
```
    from django.test import tag
```
```
    class SampleTestCase(TestCase):
```
```
        @tag('fast')
```
```
        def test_fast(self):
```
```
            ...
```
```
        @tag('slow')
```
```
        def test_slow(self):
```
```
            ...
```
```
        @tag('slow', 'core')
```
```
        def test_slow_but_core(self):
```
```
            ...
```
```
You can also tag a test case::
```
```
    @tag('slow', 'core')
```
```
    class SampleTestCase(TestCase):
```
```
        ...
```

Subclasses inherit tags from superclasses, and methods inherit tags from their

```
class. Given::
```
```
    @tag('foo')
```

    class SampleTestCaseChild(SampleTestCase):

```
        @tag('bar')
```
```
        def test(self):
```
```
            ...
```

``SampleTestCaseChild.test`` will be labeled with ``'slow'``, ``'core'``,

```
``'bar'``, and ``'foo'``.
```

Then you can choose which tests to run. For example, to run only fast tests:

```
.. console::
```
```
    $ ./manage.py test --tag=fast
```

Or to run fast tests and the core one (even though it's slow):

```
.. console::
```

    $ ./manage.py test --tag=fast --tag=core

You can also exclude tests by tag. To run core tests if they are not slow:

```
.. console::
```

    $ ./manage.py test --tag=core --exclude-tag=slow

:option:`test --exclude-tag` has precedence over :option:`test --tag`, so if a

test has two tags and you select one of them and exclude the other, the test

```
won't be run.
```
```
.. _async-tests:
```
```
Testing asynchronous code
```
```
=========================
```

If you merely want to test the output of your asynchronous views, the standard

test client will run them inside their own asynchronous loop without any extra

```
work needed on your part.
```

However, if you want to write fully-asynchronous tests for a Django project,

you will need to take several things into account.

Firstly, your tests must be ``async def`` methods on the test class (in order

to give them an asynchronous context). Django will automatically detect

any ``async def`` tests and wrap them so they run in their own event loop.

If you are testing from an asynchronous function, you must also use the

asynchronous test client. This is available as ``django.test.AsyncClient``,

or as ``self.async_client`` on any test.

.. class:: AsyncClient(enforce_csrf_checks=False, raise_request_exception=True, **defaults)

``AsyncClient`` has the same methods and signatures as the synchronous (normal)

```
test client, with two exceptions:
```

* In the initialization, arbitrary keyword arguments in ``defaults`` are added

```
  directly into the ASGI scope.
```

* The ``follow`` parameter is not supported.

* Headers passed as ``extra`` keyword arguments should not have the ``HTTP_``

  prefix required by the synchronous client (see :meth:`Client.get`). For

  example, here is how to set an HTTP ``Accept`` header::

```
    >>> c = AsyncClient()
```
```
    >>> c.get(
```
```
    ...     '/customers/details/',
```

    ...     {'name': 'fred', 'age': 7},

```
    ...     ACCEPT='application/json'
```
```
    ... )
```

Using ``AsyncClient`` any method that makes a request must be awaited::

```
    async def test_my_thing(self):
```

        response = await self.async_client.get('/some-url/')

        self.assertEqual(response.status_code, 200)

The asynchronous client can also call synchronous views; it runs through

Django's :doc:`asynchronous request path </topics/async>`, which supports both.

Any view called through the ``AsyncClient`` will get an ``ASGIRequest`` object

for its ``request`` rather than the ``WSGIRequest`` that the normal client

```
creates.
```
```
.. warning::
```

    If you are using test decorators, they must be async-compatible to ensure

    they work correctly. Django's built-in decorators will behave correctly, but

    third-party ones may appear to not execute (they will "wrap" the wrong part

    of the execution flow and not your test).

    If you need to use these decorators, then you should decorate your test

    methods with :func:`~asgiref.sync.async_to_sync` *inside* of them instead::

        from asgiref.sync import async_to_sync

        from django.test import TestCase

```
        class MyTests(TestCase):
```
```
            @mock.patch(...)
```
```
            @async_to_sync
```

            async def test_my_thing(self):

```
                ...
```
```
.. _topics-testing-email:
```
```
Email services
```
```
==============
```

If any of your Django views send email using :doc:`Django's email

functionality </topics/email>`, you probably don't want to send email each time

you run a test using that view. For this reason, Django's test runner

automatically redirects all Django-sent email to a dummy outbox. This lets you

test every aspect of sending email -- from the number of messages sent to the

contents of each message -- without actually sending the messages.

The test runner accomplishes this by transparently replacing the normal

```
email backend with a testing backend.
```

(Don't worry -- this has no effect on any other email senders outside of

Django, such as your machine's mail server, if you're running one.)

```
.. currentmodule:: django.core.mail
```
```
.. data:: django.core.mail.outbox
```

During test running, each outgoing email is saved in

``django.core.mail.outbox``. This is a list of all

:class:`~django.core.mail.EmailMessage` instances that have been sent.  The

``outbox`` attribute is a special attribute that is created *only* when the

``locmem`` email backend is used. It doesn't normally exist as part of the

:mod:`django.core.mail` module and you can't import it directly. The code below

shows how to access this attribute correctly.

Here's an example test that examines ``django.core.mail.outbox`` for length

```
and contents::
```
```
    from django.core import mail
```
```
    from django.test import TestCase
```
```
    class EmailTest(TestCase):
```
```
        def test_send_email(self):
```
```
            # Send message.
```
```
            mail.send_mail(
```

                'Subject here', 'Here is the message.',

                '[email protected]', ['[email protected]'],

```
                fail_silently=False,
```
```
            )
```

            # Test that one message has been sent.

            self.assertEqual(len(mail.outbox), 1)

            # Verify that the subject of the first message is correct.

            self.assertEqual(mail.outbox[0].subject, 'Subject here')

As noted :ref:`previously <emptying-test-outbox>`, the test outbox is emptied

at the start of every test in a Django ``*TestCase``. To empty the outbox

manually, assign the empty list to ``mail.outbox``::

```
    from django.core import mail
```
```
    # Empty the test outbox
```
```
    mail.outbox = []
```

.. _topics-testing-management-commands:

```
Management Commands
```
```
===================
```

Management commands can be tested with the

:func:`~django.core.management.call_command` function. The output can be

redirected into a ``StringIO`` instance::

```
    from io import StringIO
```

    from django.core.management import call_command

```
    from django.test import TestCase
```
```
    class ClosepollTest(TestCase):
```
```
        def test_command_output(self):
```
```
            out = StringIO()
```

            call_command('closepoll', stdout=out)

            self.assertIn('Expected output', out.getvalue())

```
.. _skipping-tests:
```
```
Skipping tests
```
```
==============
```
```
.. currentmodule:: django.test
```

The unittest library provides the :func:`@skipIf <unittest.skipIf>` and

:func:`@skipUnless <unittest.skipUnless>` decorators to allow you to skip tests

if you know ahead of time that those tests are going to fail under certain

```
conditions.
```

For example, if your test requires a particular optional library in order to

succeed, you could decorate the test case with :func:`@skipIf

<unittest.skipIf>`. Then, the test runner will report that the test wasn't

executed and why, instead of failing the test or omitting the test altogether.

To supplement these test skipping behaviors, Django provides two

additional skip decorators. Instead of testing a generic boolean,

these decorators check the capabilities of the database, and skip the

test if the database doesn't support a specific named feature.

The decorators use a string identifier to describe database features.

This string corresponds to attributes of the database connection

```
features class. See
```

:source:`django.db.backends.base.features.BaseDatabaseFeatures class

<django/db/backends/base/features.py>` for a full list of database features

that can be used as a basis for skipping tests.

.. function:: skipIfDBFeature(*feature_name_strings)

Skip the decorated test or ``TestCase`` if all of the named database features

```
are supported.
```

For example, the following test will not be executed if the database

supports transactions (e.g., it would *not* run under PostgreSQL, but

it would under MySQL with MyISAM tables)::

```
    class MyTests(TestCase):
```

        @skipIfDBFeature('supports_transactions')

        def test_transaction_behavior(self):

            # ... conditional test code

```
            pass
```

.. function:: skipUnlessDBFeature(*feature_name_strings)

Skip the decorated test or ``TestCase`` if any of the named database features

```
are *not* supported.
```

For example, the following test will only be executed if the database

supports transactions (e.g., it would run under PostgreSQL, but *not*

```
under MySQL with MyISAM tables)::
```
```
    class MyTests(TestCase):
```

        @skipUnlessDBFeature('supports_transactions')

        def test_transaction_behavior(self):

            # ... conditional test code

```
            pass
```