Django2.0手册:Testing tools

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

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 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
    LiveServerTestCase for more details.

A comprehensive test suite should use a combination of both 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 urllib.

  • To resolve URLs, the test client uses whatever URLconf is pointed-to by
    your 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, **defaults)[source]

It requires no arguments at time of construction. However, you can use
keywords 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 keywords arguments passed to
get(),
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).

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

get(path, data=None, follow=False, secure=False, **extra)[source]

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_X_REQUESTED_WITH='XMLHttpRequest')

…will send the HTTP header HTTP_X_REQUESTED_WITH to the
details view, which is a good way to test code paths that use the
django.http.HttpRequest.is_ajax() method.

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.

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.

post(path, data=None, content_type=MULTIPART_CONTENT, follow=False, secure=False, **extra)[source]

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 (e.g. text/xml for an XML
payload), the contents of data will be 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
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:

>>> c = Client()
>>> with open('wishlist.doc') as fp:
...     c.post('/customers/wishes/', {'name': 'fred', 'attachment': fp})

(The name attachment here is not relevant; use whatever name your
file-processing code expects.)

You may also provide any file-like object (e.g., StringIO or
BytesIO) as a file handle. If you’re uploading to an
ImageField, the object needs a name
attribute that passes the
validate_image_file_extension validator.
For example:

>>> from io import BytesIO
>>> img = BytesIO(b'mybinarydata')
>>> img.name = 'myimage.jpg'

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 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.

head(path, data=None, follow=False, secure=False, **extra)[source]

Makes a HEAD request on the provided path and returns a
Response object. This method works just like Client.get(),
including the follow, secure and extra arguments, except
it does not return a message body.

options(path, data=”, content_type=’application/octet-stream’, follow=False, secure=False, **extra)[source]

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
Client.get().

put(path, data=”, content_type=’application/octet-stream’, follow=False, secure=False, **extra)[source]

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
Client.get().

patch(path, data=”, content_type=’application/octet-stream’, follow=False, secure=False, **extra)[source]

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
Client.get().

delete(path, data=”, content_type=’application/octet-stream’, follow=False, secure=False, **extra)[source]

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
Client.get().

trace(path, follow=False, secure=False, **extra)[source]

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
Client.get().

login(**credentials)[source]

If your site uses Django’s authentication system
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
authentication backend you’re using
(which is configured by your 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
set_password() function to
store a correctly hashed password. Alternatively, you can use the
create_user() helper
method to create a new user with a correctly hashed password.

force_login(user, backend=None)[source]

If your site uses Django’s authentication
system
, you can use the force_login() method
to simulate the effect of a user logging into the site. Use this method
instead of 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 (is_active=False) 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 authenticate() function called by
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 using a weaker hasher while testing.

logout()[source]

If your site uses Django’s authentication system,
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 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
client

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

content

The body of the response, as a bytestring. This is the final page
content as rendered by the view, or any error message.

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'

Not using Django templates?

This attribute is only populated when using the
DjangoTemplates backend.
If you’re using another template engine,
context_data
may be a suitable alternative on responses with that attribute.

json(**kwargs)

The body of the response, parsed as JSON. Extra keyword arguments are
passed to json.loads(). For example:

>>> response = client.get('/foo/')
>>> response.json()['name']
'Arthur'

If the Content-Type header is not "application/json", then a
ValueError will be raised when trying to parse the response.

request

The request data that stimulated the response.

wsgi_request

The WSGIRequest instance generated by the test handler that
generated the response.

status_code

The HTTP status of the response, as an integer. For a full list
of defined codes, see the IANA status code registry.

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'.)

Not using Django templates?

This attribute is only populated when using the
DjangoTemplates backend.
If you’re using another template engine,
template_name
may be a suitable alternative if you only need the name of the
template used for rendering.

resolver_match

An instance of ResolverMatch for the response.
You can use the 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 be compared by name, as the functions
# generated by as_view() won't be equal
self.assertEqual(response.resolver_match.func.__name__, MyView.as_view().__name__)

If the given URL is not found, accessing this attribute will raise a
Resolver404 exception.

You can also use dictionary syntax on the response object to query the value
of any settings in the HTTP headers. For example, you could determine the
content type of a response using response['Content-Type'].

例外¶

If you point the test client at a view that raises an exception, that exception
will be visible in the test case. You can then use a standard try ... except
block or assertRaises() to test for exceptions.

The only exceptions that are not visible to the test client are
Http404,
PermissionDenied, SystemExit, and
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.

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 two attributes that store persistent state information. You
can access these properties as part of a test condition.

Client.cookies

A Python SimpleCookie object, containing the current
values of all the client cookies. See the documentation of the
http.cookies module for more.

Client.session

A dictionary-like object containing session information. See the
session documentation 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
LocaleMiddleware is enabled.

If the middleware is enabled, the language can be set by creating a cookie with
a name of 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.")

More details are in How Django discovers language preference.

If the middleware isn’t enabled, the active language may be set using
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 Explicitly setting the active language.

例如¶

The following is a simple 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)

Provided test case classes¶

Normal Python unit test classes extend a base class of
unittest.TestCase. Django provides a few extensions of this base class:

Hierarchy of Django unit testing classes (TestCase subclasses)

Hierarchy of Django unit testing classes

Converting a normal unittest.TestCase to any of the subclasses is
easy: 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[source]

A subclass of unittest.TestCase that adds this functionality:

If your tests make any database queries, use subclasses
TransactionTestCase or TestCase.

SimpleTestCase.allow_database_queries

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 allow_database_queries class attribute to True 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 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
unittest.SkipTest in setUpClass(), be sure to do it before
calling super() to avoid this.

TransactionTestCase¶

class TransactionTestCase[source]

TransactionTestCase inherits from SimpleTestCase to
add some database-specific features:

Django’s 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
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 will not see their data reloaded;
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[source]

This is the most common class to use for writing tests in Django. It inherits
from TransactionTestCase (and by extension SimpleTestCase).
If your Django application doesn’t use a database, use SimpleTestCase.

The class:

  • Wraps the tests within two nested atomic()
    blocks: one for the whole class and one for each test. Therefore, if you want
    to test some specific database transaction behavior, use
    TransactionTestCase.
  • Checks deferrable database constraints at the end of each test.

It also provides an additional method:

classmethod TestCase.setUpTestData()[source]

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().

例如:

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.

Be careful not to modify any objects created in setUpTestData() in
your test methods. Modifications to in-memory objects from setup work done
at the class level will persist between test methods. If you do need to
modify them, you could reload them in the setUp() method with
refresh_from_db(), for example.

LiveServerTestCase¶

class LiveServerTestCase[source]

LiveServerTestCase does basically the same as
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
Django dummy 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.

Changed in Django 1.11:

In older versions, Django tried a predefined port range which could be
customized in various ways including the DJANGO_LIVE_TEST_SERVER_ADDRESS
environment variable. This is removed in favor of the simpler “bind to port
0” technique.

To demonstrate how to use LiveServerTestCase, let’s write a simple Selenium
test. First of all, you need to install the selenium package into your
Python path:

$ 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 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
collectstatic. We’ll use
the 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.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:

$ ./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.

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, simply 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.

Test cases features¶

Default test client¶

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 just 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¶

SimpleTestCase.client_class

If you want to use a different Client class (for example, a subclass
with customized behavior), use the 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()

Fixture loading¶

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 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
manage.py dumpdata command. This assumes you
already have some data in your database. See the dumpdata
documentation
for more details.

Once you’ve created a fixture and placed it in a fixtures directory in one
of your INSTALLED_APPS, you can use it in your unit tests by
specifying a fixtures class attribute on your 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
    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 loaddata documentation for more
    details on defining and installing fixtures.

For performance reasons, TestCase loads fixtures once for the entire
test class, before 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 multi_db=True, fixtures will be loaded into all 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.

Multi-database support¶

TransactionTestCase.multi_db

Django sets up a test database corresponding to every database that is
defined in the DATABASES definition in your settings
file. 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 multi_db attribute on the test suite to request a full
flush.

例如:

class TestMyViews(TestCase):
    multi_db = True

    def test_index_page_view(self):
        call_some_test_code()

This test case will flush all the test databases before running
test_index_page_view.

The multi_db flag also affects into which databases the
TransactionTestCase.fixtures are loaded. By default (when
multi_db=False), fixtures are only loaded into the default database.
If multi_db=True, fixtures are loaded into all databases.

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.

SimpleTestCase.settings()[source]

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
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 LOGIN_URL setting for the code
in the with block and reset its value to the previous state afterwards.

SimpleTestCase.modify_settings()[source]

It can prove unwieldy to redefine settings that contain a list of values. In
practice, adding or removing values is often sufficient. The
modify_settings() context manager makes it
easy:

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.

override_settings()[source]

In case you want to override a setting for a test method, Django provides the
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 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/')
modify_settings()[source]

Likewise, Django provides the 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, modify_settings() is
always applied after 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 override_settings() or
modify_settings() with these settings is probably not
going to do what you expect it to do.

We do not recommend altering the DATABASES setting. Altering
the CACHES setting is possible, but a bit tricky if you are
using internals that make using of caching, like
django.contrib.sessions. For example, you will have to reinitialize
the session backend in a test that uses cached sessions and overrides
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 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 默认文件存储

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¶

As Python’s normal unittest.TestCase class implements assertion methods
such as assertTrue() and
assertEqual(), Django’s custom 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.

SimpleTestCase.assertRaisesMessage(expected_exception, expected_message, callable, *args, **kwargs)[source]
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
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')
SimpleTestCase.assertFieldOutput(fieldclass, valid, invalid, field_args=None, field_kwargs=None, empty_value=”)[source]

Asserts that a form field behaves correctly with various inputs.

Parameters:
  • fieldclass — the class of the field to be tested.
  • valid — a dictionary mapping valid inputs to their expected cleaned
    values.
  • invalid — a dictionary mapping invalid inputs to one or more raised
    error messages.
  • field_args — the args passed to instantiate the field.
  • field_kwargs — the kwargs passed to instantiate the field.
  • empty_value — the expected clean output for inputs in empty_values.

For example, the following code tests that an EmailField accepts
a@a.com as a valid email address, but rejects aaa with a reasonable
error message:

self.assertFieldOutput(EmailField, {'a@a.com': 'a@a.com'}, {'aaa': ['Enter a valid email address.']})
SimpleTestCase.assertFormError(response, form, field, errors, msg_prefix=”)[source]

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

form is the name the Form instance was given in the template
context.

field is the name of the field on the form to check. If field
has a value of None, non-field errors (errors you can access via
form.non_field_errors()) will
be checked.

errors is an error string, or a list of error strings, that are
expected as a result of form validation.

SimpleTestCase.assertFormsetError(response, formset, form_index, field, errors, msg_prefix=”)[source]

Asserts that the formset raises the provided list of errors when
rendered.

formset is the name the Formset instance was given in the template
context.

form_index is the number of the form within the Formset. If
form_index has a value of None, non-form errors (errors you can
access via formset.non_form_errors()) will be checked.

field is the name of the field on the form to check. If field
has a value of None, non-field errors (errors you can access via
form.non_field_errors()) will
be checked.

errors is an error string, or a list of error strings, that are
expected as a result of form validation.

SimpleTestCase.assertContains(response, text, count=None, status_code=200, msg_prefix=”, html=False)[source]

Asserts that a Response instance produced the given status_code and
that text appears in the content of the response. 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
assertHTMLEqual() for more details.

SimpleTestCase.assertNotContains(response, text, status_code=200, msg_prefix=”, html=False)[source]

Asserts that a Response instance produced the given status_code and
that text does not appear in the content of 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
assertHTMLEqual() for more details.

SimpleTestCase.assertTemplateUsed(response, template_name, msg_prefix=”, count=None)[source]

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

The name is 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')
SimpleTestCase.assertTemplateNotUsed(response, template_name, msg_prefix=”)[source]

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
assertTemplateUsed().

SimpleTestCase.assertRedirects(response, expected_url, status_code=302, target_status_code=200, msg_prefix=”, fetch_redirect_response=True)[source]

Asserts that the response returned a 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.

SimpleTestCase.assertHTMLEqual(html1, html2, msg=None)[source]

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.
  • Attributes without an argument are equal to attributes that equal in
    name and value (see the examples).

The following examples are valid tests and don’t raise any
AssertionError:

self.assertHTMLEqual(
    '<p>Hello <b>world!</p>',
    '''<p>
        Hello   <b>world! <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 be valid 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.

SimpleTestCase.assertHTMLNotEqual(html1, html2, msg=None)[source]

Asserts that the strings html1 and html2 are not equal. The
comparison is based on HTML semantics. See
assertHTMLEqual() for details.

html1 and html2 must be valid 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.

SimpleTestCase.assertXMLEqual(xml1, xml2, msg=None)[source]

Asserts that the strings xml1 and xml2 are equal. The
comparison is based on XML semantics. Similarly to
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 string are identical.

Output in case of error can be customized with the msg argument.

SimpleTestCase.assertXMLNotEqual(xml1, xml2, msg=None)[source]

Asserts that the strings xml1 and xml2 are not equal. The
comparison is based on XML semantics. See
assertXMLEqual() for details.

Output in case of error can be customized with the msg argument.

SimpleTestCase.assertInHTML(needle, haystack, count=None, msg_prefix=”)[source]

Asserts that the HTML fragment needle is contained in the haystack one.

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. The passed-in arguments must be valid HTML.

SimpleTestCase.assertJSONEqual(raw, expected_data, msg=None)[source]

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 json library.

Output in case of error can be customized with the msg argument.

SimpleTestCase.assertJSONNotEqual(raw, expected_data, msg=None)[source]

Asserts that the JSON fragments raw and expected_data are not equal.
See assertJSONEqual() for further details.

Output in case of error can be customized with the msg argument.

TransactionTestCase.assertQuerysetEqual(qs, values, transform=repr, ordered=True, msg=None)[source]

Asserts that a queryset qs returns a particular list of values values.

The comparison of the contents of qs and values is performed using
the function transform; by default, this means that the repr() of
each value is compared. Any other callable can be used if repr() doesn’t
provide a unique or helpful comparison.

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 values), a ValueError is
raised.

Output in case of error can be customized with the msg argument.

TransactionTestCase.assertNumQueries(num, func, *args, **kwargs)[source]

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. 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))

你也可以用它作为上下文管理器:

with self.assertNumQueries(2):
    Person.objects.create(name="Aaron")
    Person.objects.create(name="Daniel")

标记测试¶

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):
    ...

Then you can choose which tests to run. For example, to run only fast tests:

$ ./manage.py test --tag=fast

Or to run fast tests and the core one (even though it’s slow):

$ ./manage.py test --tag=fast --tag=core

You can also exclude tests by tag. To run core tests if they are not slow:

$ ./manage.py test --tag=core --exclude-tag=slow

test --exclude-tag has precedence over 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.

Email services¶

If any of your Django views send email using Django’s email
functionality
, 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.)

django.core.mail.outbox

During test running, each outgoing email is saved in
django.core.mail.outbox. This is a simple list of all
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
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.',
            'from@example.com', ['to@example.com'],
            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 previously, 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 = []

管理命令¶

Management commands can be tested with the
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())

忽略测试¶

The unittest library provides the @skipIf and
@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 @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 django.db.backends.BaseDatabaseFeatures
class for a full list of database features that can be used as a basis
for skipping tests.

skipIfDBFeature(*feature_name_strings)[source]

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
skipUnlessDBFeature(*feature_name_strings)[source]

Skip the decorated test or TestCase if any of the named database features
are not supported.

例如,接下来的测试仅在支持事务的数据库下执行(如:可以是PostgreSQL,但不可以是使用MyISAM数据库引擎的MySQL):

class MyTests(TestCase):
    @skipUnlessDBFeature('supports_transactions')
    def test_transaction_behavior(self):
        # ... conditional test code
        pass