=========================== Testing Django applications =========================== .. module:: django.test :synopsis: Testing tools for Django applications. Automated testing is an extremely useful bug-killing tool for the modern Web developer. You can use a collection of tests -- a **test suite** -- to solve, or avoid, a number of problems: * When you're writing new code, you can use tests to validate your code works as expected. * When you're refactoring or modifying old code, you can use tests to ensure your changes haven't affected your application's behavior unexpectedly. Testing a Web application is a complex task, because a Web application is made of several layers of logic -- from HTTP-level request handling, to form validation and processing, to template rendering. With Django's test-execution framework and assorted utilities, you can simulate requests, insert test data, inspect your application's output and generally verify your code is doing what it should be doing. The best part is, it's really easy. This document is split into two primary sections. First, we explain how to write tests with Django. Then, we explain how to run them. Writing tests ============= There are two primary ways to write tests with Django, corresponding to the two test frameworks that ship in the Python standard library. The two frameworks are: * **Unit tests** -- tests that are expressed as methods on a Python class that subclasses :class:`unittest.TestCase` or Django's customized :class:`TestCase`. For example:: import unittest class MyFuncTestCase(unittest.TestCase): def testBasic(self): a = ['larry', 'curly', 'moe'] self.assertEqual(my_func(a, 0), 'larry') self.assertEqual(my_func(a, 1), 'curly') * **Doctests** -- tests that are embedded in your functions' docstrings and are written in a way that emulates a session of the Python interactive interpreter. For example:: def my_func(a_list, idx): """ >>> a = ['larry', 'curly', 'moe'] >>> my_func(a, 0) 'larry' >>> my_func(a, 1) 'curly' """ return a_list[idx] We'll discuss choosing the appropriate test framework later, however, most experienced developers prefer unit tests. You can also use any *other* Python test framework, as we'll explain in a bit. Writing unit tests ------------------ Django's unit tests use a Python standard library module: :mod:`unittest`. This module defines tests in class-based approach. .. admonition:: unittest2 Python 2.7 introduced some major changes to the unittest library, adding some extremely useful features. To ensure that every Django project can benefit from these new features, Django ships with a copy of unittest2_, a copy of the Python 2.7 unittest library, backported for Python 2.5 compatibility. To access this library, Django provides the :mod:`django.utils.unittest` module alias. If you are using Python 2.7, or you have installed unittest2 locally, Django will map the alias to the installed version of the unittest library. Otherwise, Django will use its own bundled version of unittest2. To use this alias, simply use:: from django.utils import unittest wherever you would have historically used:: import unittest If you want to continue to use the base unittest library, you can -- you just won't get any of the nice new unittest2 features. .. _unittest2: http://pypi.python.org/pypi/unittest2 For a given Django application, the test runner looks for unit tests in two places: * The ``models.py`` file. The test runner looks for any subclass of :class:`unittest.TestCase` in this module. * A file called ``tests.py`` in the application directory -- i.e., the directory that holds ``models.py``. Again, the test runner looks for any subclass of :class:`unittest.TestCase` in this module. Here is an example :class:`unittest.TestCase` subclass:: from django.utils import unittest from myapp.models import Animal class AnimalTestCase(unittest.TestCase): def setUp(self): self.lion = Animal.objects.create(name="lion", sound="roar") self.cat = Animal.objects.create(name="cat", sound="meow") def test_animals_can_speak(self): """Animals that can speak are correctly identified""" self.assertEqual(self.lion.speak(), 'The lion says "roar"') self.assertEqual(self.cat.speak(), 'The cat says "meow"') When you :ref:`run your tests `, the default behavior of the test utility is to find all the test cases (that is, subclasses of :class:`unittest.TestCase`) in ``models.py`` and ``tests.py``, automatically build a test suite out of those test cases, and run that suite. There is a second way to define the test suite for a module: if you define a function called ``suite()`` in either ``models.py`` or ``tests.py``, the Django test runner will use that function to construct the test suite for that module. This follows the `suggested organization`_ for unit tests. See the Python documentation for more details on how to construct a complex test suite. For more details about :mod:`unittest`, see the Python documentation. .. _suggested organization: http://docs.python.org/library/unittest.html#organizing-tests Writing doctests ---------------- Doctests use Python's standard :mod:`doctest` module, which searches your docstrings for statements that resemble a session of the Python interactive interpreter. A full explanation of how :mod:`doctest` works is out of the scope of this document; read Python's official documentation for the details. .. admonition:: What's a **docstring**? A good explanation of docstrings (and some guidelines for using them effectively) can be found in :pep:`257`: A docstring is a string literal that occurs as the first statement in a module, function, class, or method definition. Such a docstring becomes the ``__doc__`` special attribute of that object. For example, this function has a docstring that describes what it does:: def add_two(num): "Return the result of adding two to the provided number." return num + 2 Because tests often make great documentation, putting tests directly in your docstrings is an effective way to document *and* test your code. As with unit tests, for a given Django application, the test runner looks for doctests in two places: * The ``models.py`` file. You can define module-level doctests and/or a doctest for individual models. It's common practice to put application-level doctests in the module docstring and model-level doctests in the model docstrings. * A file called ``tests.py`` in the application directory -- i.e., the directory that holds ``models.py``. This file is a hook for any and all doctests you want to write that aren't necessarily related to models. This example doctest is equivalent to the example given in the unittest section above:: # models.py from django.db import models class Animal(models.Model): """ An animal that knows how to make noise # Create some animals >>> lion = Animal.objects.create(name="lion", sound="roar") >>> cat = Animal.objects.create(name="cat", sound="meow") # Make 'em speak >>> lion.speak() 'The lion says "roar"' >>> cat.speak() 'The cat says "meow"' """ name = models.CharField(max_length=20) sound = models.CharField(max_length=20) def speak(self): return 'The %s says "%s"' % (self.name, self.sound) When you :ref:`run your tests `, the test runner will find this docstring, notice that portions of it look like an interactive Python session, and execute those lines while checking that the results match. In the case of model tests, note that the test runner takes care of creating its own test database. That is, any test that accesses a database -- by creating and saving model instances, for example -- will not affect your production database. However, the database is not refreshed between doctests, so if your doctest requires a certain state you should consider flushing the database or loading a fixture. (See the section on fixtures, below, for more on this.) Note that to use this feature, the database user Django is connecting as must have ``CREATE DATABASE`` rights. For more details about :mod:`doctest`, see the Python documentation. Which should I use? ------------------- Because Django supports both of the standard Python test frameworks, it's up to you and your tastes to decide which one to use. You can even decide to use *both*. For developers new to testing, however, this choice can seem confusing. Here, then, are a few key differences to help you decide which approach is right for you: * If you've been using Python for a while, :mod:`doctest` will probably feel more "pythonic". It's designed to make writing tests as easy as possible, so it requires no overhead of writing classes or methods. You simply put tests in docstrings. This has the added advantage of serving as documentation (and correct documentation, at that!). However, while doctests are good for some simple example code, they are not very good if you want to produce either high quality, comprehensive tests or high quality documentation. Test failures are often difficult to debug as it can be unclear exactly why the test failed. Thus, doctests should generally be avoided and used primarily for documentation examples only. * The :mod:`unittest` framework will probably feel very familiar to developers coming from Java. :mod:`unittest` is inspired by Java's JUnit, so you'll feel at home with this method if you've used JUnit or any test framework inspired by JUnit. * If you need to write a bunch of tests that share similar code, then you'll appreciate the :mod:`unittest` framework's organization around classes and methods. This makes it easy to abstract common tasks into common methods. The framework also supports explicit setup and/or cleanup routines, which give you a high level of control over the environment in which your test cases are run. * If you're writing tests for Django itself, you should use :mod:`unittest`. .. _running-tests: Running tests ============= Once you've written tests, run them using the :djadmin:`test` command of your project's ``manage.py`` utility:: $ ./manage.py test By default, this will run every test in every application in :setting:`INSTALLED_APPS`. If you only want to run tests for a particular application, add the application name to the command line. For example, if your :setting:`INSTALLED_APPS` contains ``'myproject.polls'`` and ``'myproject.animals'``, you can run the ``myproject.animals`` unit tests alone with this command:: $ ./manage.py test animals Note that we used ``animals``, not ``myproject.animals``. You can be even *more* specific by naming an individual test case. To run a single test case in an application (for example, the ``AnimalTestCase`` described in the "Writing unit tests" section), add the name of the test case to the label on the command line:: $ ./manage.py test animals.AnimalTestCase And it gets even more granular than that! To run a *single* test method inside a test case, add the name of the test method to the label:: $ ./manage.py test animals.AnimalTestCase.test_animals_can_speak You can use the same rules if you're using doctests. Django will use the test label as a path to the test method or class that you want to run. If your ``models.py`` or ``tests.py`` has a function with a doctest, or class with a class-level doctest, you can invoke that test by appending the name of the test method or class to the label:: $ ./manage.py test animals.classify If you want to run the doctest for a specific method in a class, add the name of the method to the label:: $ ./manage.py test animals.Classifier.run If you're using a ``__test__`` dictionary to specify doctests for a module, Django will use the label as a key in the ``__test__`` dictionary for defined in ``models.py`` and ``tests.py``. If you press ``Ctrl-C`` while the tests are running, the test runner will wait for the currently running test to complete and then exit gracefully. During a graceful exit the test runner will output details of any test failures, report on how many tests were run and how many errors and failures were encountered, and destroy any test databases as usual. Thus pressing ``Ctrl-C`` can be very useful if you forget to pass the :djadminopt:`--failfast` option, notice that some tests are unexpectedly failing, and want to get details on the failures without waiting for the full test run to complete. If you do not want to wait for the currently running test to finish, you can press ``Ctrl-C`` a second time and the test run will halt immediately, but not gracefully. No details of the tests run before the interruption will be reported, and any test databases created by the run will not be destroyed. .. admonition:: Test with warnings enabled It's a good idea to run your tests with Python warnings enabled: ``python -Wall manage.py test``. The ``-Wall`` flag tells Python to display deprecation warnings. Django, like many other Python libraries, uses these warnings to flag when features are going away. It also might flag areas in your code that aren't strictly wrong but could benefit from a better implementation. Running tests outside the test runner ------------------------------------- If you want to run tests outside of ``./manage.py test`` -- for example, from a shell prompt -- you will need to set up the test environment first. Django provides a convenience method to do this:: >>> from django.test.utils import setup_test_environment >>> setup_test_environment() This convenience method sets up the test database, and puts other Django features into modes that allow for repeatable testing. The call to :meth:`~django.test.utils.setup_test_environment` is made automatically as part of the setup of `./manage.py test`. You only need to manually invoke this method if you're not using running your tests via Django's test runner. The test database ----------------- Tests that require a database (namely, model tests) will not use your "real" (production) database. Separate, blank databases are created for the tests. Regardless of whether the tests pass or fail, the test databases are destroyed when all the tests have been executed. By default the test databases get their names by prepending ``test_`` to the value of the :setting:`NAME` settings for the databases defined in :setting:`DATABASES`. When using the SQLite database engine the tests will by default use an in-memory database (i.e., the database will be created in memory, bypassing the filesystem entirely!). If you want to use a different database name, specify :setting:`TEST_NAME` in the dictionary for any given database in :setting:`DATABASES`. Aside from using a separate database, the test runner will otherwise use all of the same database settings you have in your settings file: :setting:`ENGINE`, :setting:`USER`, :setting:`HOST`, etc. The test database is created by the user specified by :setting:`USER`, so you'll need to make sure that the given user account has sufficient privileges to create a new database on the system. For fine-grained control over the character encoding of your test database, use the :setting:`TEST_CHARSET` option. If you're using MySQL, you can also use the :setting:`TEST_COLLATION` option to control the particular collation used by the test database. See the :doc:`settings documentation ` for details of these advanced settings. .. _topics-testing-masterslave: Testing master/slave configurations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If you're testing a multiple database configuration with master/slave replication, this strategy of creating test databases poses a problem. When the test databases are created, there won't be any replication, and as a result, data created on the master won't be seen on the slave. To compensate for this, Django allows you to define that a database is a *test mirror*. Consider the following (simplified) example database configuration:: DATABASES = { 'default': { 'ENGINE': 'django.db.backends.mysql', 'NAME': 'myproject', 'HOST': 'dbmaster', # ... plus some other settings }, 'slave': { 'ENGINE': 'django.db.backends.mysql', 'NAME': 'myproject', 'HOST': 'dbslave', 'TEST_MIRROR': 'default' # ... plus some other settings } } In this setup, we have two database servers: ``dbmaster``, described by the database alias ``default``, and ``dbslave`` described by the alias ``slave``. As you might expect, ``dbslave`` has been configured by the database administrator as a read slave of ``dbmaster``, so in normal activity, any write to ``default`` will appear on ``slave``. If Django created two independent test databases, this would break any tests that expected replication to occur. However, the ``slave`` database has been configured as a test mirror (using the :setting:`TEST_MIRROR` setting), indicating that under testing, ``slave`` should be treated as a mirror of ``default``. When the test environment is configured, a test version of ``slave`` will *not* be created. Instead the connection to ``slave`` will be redirected to point at ``default``. As a result, writes to ``default`` will appear on ``slave`` -- but because they are actually the same database, not because there is data replication between the two databases. .. _topics-testing-creation-dependencies: Controlling creation order for test databases ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ By default, Django will always create the ``default`` database first. However, no guarantees are made on the creation order of any other databases in your test setup. If your database configuration requires a specific creation order, you can specify the dependencies that exist using the :setting:`TEST_DEPENDENCIES` setting. Consider the following (simplified) example database configuration:: DATABASES = { 'default': { # ... db settings 'TEST_DEPENDENCIES': ['diamonds'] }, 'diamonds': { # ... db settings }, 'clubs': { # ... db settings 'TEST_DEPENDENCIES': ['diamonds'] }, 'spades': { # ... db settings 'TEST_DEPENDENCIES': ['diamonds','hearts'] }, 'hearts': { # ... db settings 'TEST_DEPENDENCIES': ['diamonds','clubs'] } } Under this configuration, the ``diamonds`` database will be created first, as it is the only database alias without dependencies. The ``default`` and ``clubs`` alias will be created next (although the order of creation of this pair is not guaranteed); then ``hearts``; and finally ``spades``. If there are any circular dependencies in the :setting:`TEST_DEPENDENCIES` definition, an ``ImproperlyConfigured`` exception will be raised. Order in which tests are executed --------------------------------- In order to guarantee that all ``TestCase`` code starts with a clean database, the Django test runner reorders tests in the following way: * First, all unittests (including :class:`unittest.TestCase`, :class:`~django.test.SimpleTestCase`, :class:`~django.test.TestCase` and :class:`~django.test.TransactionTestCase`) are run with no particular ordering guaranteed nor enforced among them. * Then any other tests (e.g. doctests) that may alter the database without restoring it to its original state are run. .. versionchanged:: 1.5 Before Django 1.5, the only guarantee was that :class:`~django.test.TestCase` tests were always ran first, before any other tests. .. note:: The new ordering of tests may reveal unexpected dependencies on test case ordering. This is the case with doctests that relied on state left in the database by a given :class:`~django.test.TransactionTestCase` test, they must be updated to be able to run independently. Other test conditions --------------------- Regardless of the value of the :setting:`DEBUG` setting in your configuration file, all Django tests run with :setting:`DEBUG`\=False. This is to ensure that the observed output of your code matches what will be seen in a production setting. Caches are not cleared after each test, and running "manage.py test fooapp" can insert data from the tests into the cache of a live system if you run your tests in production because, unlike databases, a separate "test cache" is not used. This behavior `may change`_ in the future. .. _may change: https://code.djangoproject.com/ticket/11505 Understanding the test output ----------------------------- When you run your tests, you'll see a number of messages as the test runner prepares itself. You can control the level of detail of these messages with the ``verbosity`` option on the command line:: Creating test database... Creating table myapp_animal Creating table myapp_mineral Loading 'initial_data' fixtures... No fixtures found. This tells you that the test runner is creating a test database, as described in the previous section. Once the test database has been created, Django will run your tests. If everything goes well, you'll see something like this:: ---------------------------------------------------------------------- Ran 22 tests in 0.221s OK If there are test failures, however, you'll see full details about which tests failed:: ====================================================================== FAIL: Doctest: ellington.core.throttle.models ---------------------------------------------------------------------- Traceback (most recent call last): File "/dev/django/test/doctest.py", line 2153, in runTest raise self.failureException(self.format_failure(new.getvalue())) AssertionError: Failed doctest test for myapp.models File "/dev/myapp/models.py", line 0, in models ---------------------------------------------------------------------- File "/dev/myapp/models.py", line 14, in myapp.models Failed example: throttle.check("actor A", "action one", limit=2, hours=1) Expected: True Got: False ---------------------------------------------------------------------- Ran 2 tests in 0.048s FAILED (failures=1) A full explanation of this error output is beyond the scope of this document, but it's pretty intuitive. You can consult the documentation of Python's :mod:`unittest` library for details. Note that the return code for the test-runner script is 1 for any number of failed and erroneous tests. If all the tests pass, the return code is 0. This feature is useful if you're using the test-runner script in a shell script and need to test for success or failure at that level. Speeding up the tests --------------------- In recent versions of Django, the default password hasher is rather slow by design. If during your tests you are authenticating many users, you may want to use a custom settings file and set the :setting:`PASSWORD_HASHERS` setting to a faster hashing algorithm:: PASSWORD_HASHERS = ( 'django.contrib.auth.hashers.MD5PasswordHasher', ) Don't forget to also include in :setting:`PASSWORD_HASHERS` any hashing algorithm used in fixtures, if any. .. _topics-testing-code-coverage: Integration with coverage.py ---------------------------- Code coverage describes how much source code has been tested. It shows which parts of your code are being exercised by tests and which are not. It's an important part of testing applications, so it's strongly recommended to check the coverage of your tests. Django can be easily integrated with `coverage.py`_, a tool for measuring code coverage of Python programs. First, `install coverage.py`_. Next, run the following from your project folder containing ``manage.py``:: coverage run --source='.' manage.py test myapp This runs your tests and collects coverage data of the executed files in your project. You can see a report of this data by typing following command:: coverage report Note that some Django code was executed while running tests, but it is not listed here because of the ``source`` flag passed to the previous command. For more options like annotated HTML listings detailing missed lines, see the `coverage.py`_ docs. .. _coverage.py: http://nedbatchelder.com/code/coverage/ .. _install coverage.py: http://pypi.python.org/pypi/coverage Testing tools ============= Django provides a small set of tools that come in handy when writing tests. .. _test-client: The test client --------------- .. module:: django.test.client :synopsis: Django's 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. * Test that the correct view is executed for a given URL. * 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 view is being called and that the view is collecting 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 :class:`~django.test.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.Client`` and retrieve Web pages:: >>> from django.test.client import Client >>> c = Client() >>> response = c.post('/login/', {'username': 'john', 'password': 'smith'}) >>> response.status_code 200 >>> response = c.get('/customer/details/') >>> response.content '>> c.get('/login/') This is incorrect:: >>> c.get('http://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` or :mod:`urllib2`. * 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.Client`` class to make requests. .. class:: Client(enforce_csrf_checks=False, **defaults) 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 :meth:`~django.test.client.Client.get()`, :meth:`~django.test.client.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). Once you have a ``Client`` instance, you can call any of the following methods: .. method:: Client.get(path, data={}, follow=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_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 :meth:`django.http.HttpRequest.is_ajax()` 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: http://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 [(u'http://testserver/next/', 302), (u'http://testserver/final/', 302)] .. method:: Client.post(path, data={}, content_type=MULTIPART_CONTENT, follow=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`` (e.g. :mimetype:`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 :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 ``', '') ``html1`` and ``html2`` must be valid HTML. An ``AssertionError`` will be raised if one of them cannot be parsed. .. method:: SimpleTestCase.assertHTMLNotEqual(html1, html2, msg=None) .. versionadded:: 1.4 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 be valid HTML. An ``AssertionError`` will be raised if one of them cannot be parsed. .. method:: SimpleTestCase.assertXMLEqual(xml1, xml2, msg=None) .. versionadded:: 1.5 Asserts that the strings ``xml1`` and ``xml2`` are equal. The comparison is based on XML semantics. Similarily to :meth:`~SimpleTestCase.assertHTMLEqual`, the comparison is made on parsed content, hence only semantic differences are considered, not syntax differences. When unvalid XML is passed in any parameter, an ``AssertionError`` is always raised, even if both string are identical. .. method:: SimpleTestCase.assertXMLNotEqual(xml1, xml2, msg=None) .. versionadded:: 1.5 Asserts that the strings ``xml1`` and ``xml2`` are *not* equal. The comparison is based on XML semantics. See :meth:`~SimpleTestCase.assertXMLEqual` for details. .. _topics-testing-email: Email services -------------- If any of your Django views send email using :doc:`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.) .. 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 simple 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.', '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 :ref:`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 = [] .. _skipping-tests: Skipping tests -------------- .. currentmodule:: django.test The unittest library provides the :func:`@skipIf ` and :func:`@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 `. 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 :class:`~django.db.backends.BaseDatabaseFeatures` class for a full list of database features that can be used as a basis for skipping tests. .. function:: skipIfDBFeature(feature_name_string) Skip the decorated test if the named database feature is 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 .. function:: skipUnlessDBFeature(feature_name_string) Skip the decorated test if the named database feature is *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 Live test server ---------------- .. versionadded:: 1.4 .. currentmodule:: django.test .. 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 ` such as, for example, the Selenium_ client, to execute a series of functional tests inside a browser and simulate a real user's actions. By default the live server's address is `'localhost:8081'` and the full URL can be accessed during the tests with ``self.live_server_url``. If you'd like to change the default address (in the case, for example, where the 8081 port is already taken) then you may pass a different one to the :djadmin:`test` command via the :djadminopt:`--liveserver` option, for example: .. code-block:: bash ./manage.py test --liveserver=localhost:8082 Another way of changing the default server address is by setting the `DJANGO_LIVE_TEST_SERVER_ADDRESS` environment variable somewhere in your code (for example, in a :ref:`custom test runner`): .. code-block:: python import os os.environ['DJANGO_LIVE_TEST_SERVER_ADDRESS'] = 'localhost:8082' In the case where the tests are run by multiple processes in parallel (for example, in the context of several simultaneous `continuous integration`_ builds), the processes will compete for the same address, and therefore your tests might randomly fail with an "Address already in use" error. To avoid this problem, you can pass a comma-separated list of ports or ranges of ports (at least as many as the number of potential parallel processes). For example: .. code-block:: bash ./manage.py test --liveserver=localhost:8082,8090-8100,9000-9200,7041 Then, during test execution, each new live test server will try every specified port until it finds one that is free and takes it. .. _continuous integration: http://en.wikipedia.org/wiki/Continuous_integration 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: .. code-block:: bash pip install selenium Then, add a ``LiveServerTestCase``-based test to your app's tests module (for example: ``myapp/tests.py``). The code for this test may look as follows: .. code-block:: python from django.test import LiveServerTestCase from selenium.webdriver.firefox.webdriver import WebDriver class MySeleniumTests(LiveServerTestCase): fixtures = ['user-data.json'] @classmethod def setUpClass(cls): cls.selenium = WebDriver() super(MySeleniumTests, cls).setUpClass() @classmethod def tearDownClass(cls): cls.selenium.quit() super(MySeleniumTests, cls).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: .. code-block:: bash ./manage.py test myapp.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: http://seleniumhq.org/ .. _selenium package: http://pypi.python.org/pypi/selenium .. _full reference: http://selenium-python.readthedocs.org/en/latest/api.html .. _Firefox: http://www.mozilla.com/firefox/ .. note:: ``LiveServerTestCase`` makes use of the :doc:`staticfiles contrib app ` so you'll need to have your project configured accordingly (in particular by setting :setting:`STATIC_URL`). .. 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 `` HTML tag is found in the response (requires Selenium > 2.13): .. code-block:: python 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 `` 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: http://code.google.com/p/selenium/wiki/FrequentlyAskedQuestions#Q:_WebDriver_fails_to_find_elements_/_Does_not_block_on_page_loa .. _Selenium documentation: http://seleniumhq.org/docs/04_webdriver_advanced.html#explicit-waits Using different testing frameworks ================================== Clearly, :mod:`doctest` and :mod:`unittest` are not the only Python testing frameworks. While Django doesn't provide explicit support for alternative frameworks, it does provide a way to invoke tests constructed for an alternative framework as if they were normal Django tests. When you run ``./manage.py test``, Django looks at the :setting:`TEST_RUNNER` setting to determine what to do. By default, :setting:`TEST_RUNNER` points to ``'django.test.simple.DjangoTestSuiteRunner'``. This class defines the default Django testing behavior. This behavior involves: #. Performing global pre-test setup. #. Looking for unit tests and doctests in the ``models.py`` and ``tests.py`` files in each installed application. #. Creating the test databases. #. Running ``syncdb`` to install models and initial data into the test databases. #. Running the unit tests and doctests that are found. #. Destroying the test databases. #. Performing global post-test teardown. If you define your own test runner class and point :setting:`TEST_RUNNER` at that class, Django will execute your test runner whenever you run ``./manage.py test``. In this way, it is possible to use any test framework that can be executed from Python code, or to modify the Django test execution process to satisfy whatever testing requirements you may have. .. _topics-testing-test_runner: Defining a test runner ---------------------- .. currentmodule:: django.test.simple A test runner is a class defining a ``run_tests()`` method. Django ships with a ``DjangoTestSuiteRunner`` class that defines the default Django testing behavior. This class defines the ``run_tests()`` entry point, plus a selection of other methods that are used to by ``run_tests()`` to set up, execute and tear down the test suite. .. class:: DjangoTestSuiteRunner(verbosity=1, interactive=True, failfast=True, **kwargs) ``verbosity`` determines the amount of notification and debug information that will be printed to the console; ``0`` is no output, ``1`` is normal output, and ``2`` is verbose output. If ``interactive`` is ``True``, the test suite has permission to ask the user for instructions when the test suite is executed. An example of this behavior would be asking for permission to delete an existing test database. If ``interactive`` is ``False``, the test suite must be able to run without any manual intervention. If ``failfast`` is ``True``, the test suite will stop running after the first test failure is detected. Django will, from time to time, extend the capabilities of the test runner by adding new arguments. The ``**kwargs`` declaration allows for this expansion. If you subclass ``DjangoTestSuiteRunner`` or write your own test runner, ensure accept and handle the ``**kwargs`` parameter. .. versionadded:: 1.4 Your test runner may also define additional command-line options. If you add an ``option_list`` attribute to a subclassed test runner, those options will be added to the list of command-line options that the :djadmin:`test` command can use. Attributes ~~~~~~~~~~ .. attribute:: DjangoTestSuiteRunner.option_list .. versionadded:: 1.4 This is the tuple of ``optparse`` options which will be fed into the management command's ``OptionParser`` for parsing arguments. See the documentation for Python's ``optparse`` module for more details. Methods ~~~~~~~ .. method:: DjangoTestSuiteRunner.run_tests(test_labels, extra_tests=None, **kwargs) Run the test suite. ``test_labels`` is a list of strings describing the tests to be run. A test label can take one of three forms: * ``app.TestCase.test_method`` -- Run a single test method in a test case. * ``app.TestCase`` -- Run all the test methods in a test case. * ``app`` -- Search for and run all tests in the named application. If ``test_labels`` has a value of ``None``, the test runner should run search for tests in all the applications in :setting:`INSTALLED_APPS`. ``extra_tests`` is a list of extra ``TestCase`` instances to add to the suite that is executed by the test runner. These extra tests are run in addition to those discovered in the modules listed in ``test_labels``. This method should return the number of tests that failed. .. method:: DjangoTestSuiteRunner.setup_test_environment(**kwargs) Sets up the test environment ready for testing. .. method:: DjangoTestSuiteRunner.build_suite(test_labels, extra_tests=None, **kwargs) Constructs a test suite that matches the test labels provided. ``test_labels`` is a list of strings describing the tests to be run. A test label can take one of three forms: * ``app.TestCase.test_method`` -- Run a single test method in a test case. * ``app.TestCase`` -- Run all the test methods in a test case. * ``app`` -- Search for and run all tests in the named application. If ``test_labels`` has a value of ``None``, the test runner should run search for tests in all the applications in :setting:`INSTALLED_APPS`. ``extra_tests`` is a list of extra ``TestCase`` instances to add to the suite that is executed by the test runner. These extra tests are run in addition to those discovered in the modules listed in ``test_labels``. Returns a ``TestSuite`` instance ready to be run. .. method:: DjangoTestSuiteRunner.setup_databases(**kwargs) Creates the test databases. Returns a data structure that provides enough detail to undo the changes that have been made. This data will be provided to the ``teardown_databases()`` function at the conclusion of testing. .. method:: DjangoTestSuiteRunner.run_suite(suite, **kwargs) Runs the test suite. Returns the result produced by the running the test suite. .. method:: DjangoTestSuiteRunner.teardown_databases(old_config, **kwargs) Destroys the test databases, restoring pre-test conditions. ``old_config`` is a data structure defining the changes in the database configuration that need to be reversed. It is the return value of the ``setup_databases()`` method. .. method:: DjangoTestSuiteRunner.teardown_test_environment(**kwargs) Restores the pre-test environment. .. method:: DjangoTestSuiteRunner.suite_result(suite, result, **kwargs) Computes and returns a return code based on a test suite, and the result from that test suite. Testing utilities ----------------- .. module:: django.test.utils :synopsis: Helpers to write custom test runners. To assist in the creation of your own test runner, Django provides a number of utility methods in the ``django.test.utils`` module. .. function:: setup_test_environment() Performs any global pre-test setup, such as the installing the instrumentation of the template rendering system and setting up the dummy email outbox. .. function:: teardown_test_environment() Performs any global post-test teardown, such as removing the black magic hooks into the template system and restoring normal email services. .. currentmodule:: django.db.connection.creation The creation module of the database backend (``connection.creation``) also provides some utilities that can be useful during testing. .. function:: create_test_db([verbosity=1, autoclobber=False]) Creates a new test database and runs ``syncdb`` against it. ``verbosity`` has the same behavior as in ``run_tests()``. ``autoclobber`` describes the behavior that will occur if a database with the same name as the test database is discovered: * If ``autoclobber`` is ``False``, the user will be asked to approve destroying the existing database. ``sys.exit`` is called if the user does not approve. * If autoclobber is ``True``, the database will be destroyed without consulting the user. Returns the name of the test database that it created. ``create_test_db()`` has the side effect of modifying the value of :setting:`NAME` in :setting:`DATABASES` to match the name of the test database. .. function:: destroy_test_db(old_database_name, [verbosity=1]) Destroys the database whose name is the value of :setting:`NAME` in :setting:`DATABASES`, and sets :setting:`NAME` to the value of ``old_database_name``. The ``verbosity`` argument has the same behavior as for :class:`~django.test.simple.DjangoTestSuiteRunner`.