[TOC=3] ## Introducing automated testing ### What are automated tests? Tests are simple routines that check the operation of your code. Testing operates at different levels. Some tests might apply to a tiny detail (*does a particular model method return values as expected?*) while others examine the overall operation of the software (*does a sequence of user inputs on the site produce the desired result?*). That’s no different from the kind of testing we did earlier in the book, using the shell to examine the behavior of a method, or running the application and entering data to check how it behaves. What’s different in *automated* tests is that the testing work is done for you by the system. You create a set of tests once, and then as you make changes to your app, you can check that your code still works as you originally intended, without having to perform time consuming manual testing. ### Why you need to create tests So why create tests, and why now? You may feel that you have quite enough on your plate just learning Python/Django, and having yet another thing to learn and do may seem overwhelming and perhaps unnecessary. After all, our polls application is working quite happily now; going through the trouble of creating automated tests is not going to make it work any better. If creating the polls application is the last bit of Django programming you will ever do, then true, you don’t need to know how to create automated tests. But, if that’s not the case, now is an excellent time to learn. #### TESTS WILL SAVE YOU TIME Up to a certain point, ‘checking that it seems to work’ will be a satisfactory test. In a more sophisticated application, you might have dozens of complex interactions between components. A change in any of those components could have unexpected consequences on the application’s behavior. Checking that it still ‘seems to work’ could mean running through your code’s functionality with twenty different variations of your test data just to make sure you haven’t broken something – not a good use of your time. That’s especially true when automated tests could do this for you in seconds. If something’s gone wrong, tests will also assist in identifying the code that’s causing the unexpected behavior. Sometimes it may seem a chore to tear yourself away from your productive, creative programming work to face the unglamorous and unexciting business of writing tests, particularly when you know your code is working properly. However, the task of writing tests is a lot more fulfilling than spending hours testing your application manually or trying to identify the cause of a newly-introduced problem. #### TESTS DON’T JUST IDENTIFY PROBLEMS, THEY PREVENT THEM It’s a mistake to think of tests merely as a negative aspect of development. Without tests, the purpose or intended behavior of an application might be rather opaque. Even when it’s your own code, you will sometimes find yourself poking around in it trying to find out what exactly it’s doing. Tests change that; they light up your code from the inside, and when something goes wrong, they focus light on the part that has gone wrong – *even if you hadn’t even realized it had gone wrong*. #### TESTS MAKE YOUR CODE MORE ATTRACTIVE You might have created a brilliant piece of software, but you will find that many other developers will simply refuse to look at it because it lacks tests; without tests, they won’t trust it. Jacob Kaplan-Moss, one of Django’s original developers, says “Code without tests is broken by design.” That other developers want to see tests in your software before they take it seriously is yet another reason for you to start writing tests. #### TESTS HELP TEAMS WORK TOGETHER The previous points are written from the point of view of a single developer maintaining an application. Complex applications will be maintained by teams. Tests guarantee that colleagues don’t inadvertently break your code (and that you don’t break theirs without knowing). If you want to make a living as a Django programmer, you must be good at writing tests! ## Basic testing strategies There are many ways to approach writing tests. Some programmers follow a discipline called “[test-driven development](http://en.wikipedia.org/wiki/Test-driven_development)“; they actually write their tests before they write their code. This might seem counter-intuitive, but in fact it’s similar to what most people will often do anyway: they describe a problem, then create some code to solve it. Test-driven development simply formalizes the problem in a Python test case. More often, a newcomer to testing will create some code and later decide that it should have some tests. Perhaps it would have been better to write some tests earlier, but it’s never too late to get started. Sometimes it’s difficult to figure out where to get started with writing tests. If you have written several thousand lines of Python, choosing something to test might not be easy. In such a case, it’s fruitful to write your first test the next time you make a change, either when you add a new feature or fix a bug. ## Writing tests Django’s unit tests use a Python standard library module: `unittest`. This module defines tests using a class-based approach. Here is an example which subclasses from `django.test.TestCase`, which is a subclass of `unittest.TestCase`that runs each test inside a transaction to provide isolation: ~~~ from django.test import TestCase from myapp.models import Animal class AnimalTestCase(TestCase): def setUp(self): Animal.objects.create(name="lion", sound="roar") Animal.objects.create(name="cat", sound="meow") def test_animals_can_speak(self): """Animals that can speak are correctly identified""" lion = Animal.objects.get(name="lion") cat = Animal.objects.get(name="cat") self.assertEqual(lion.speak(), 'The lion says "roar"') self.assertEqual(cat.speak(), 'The cat says "meow"') ~~~ When you run your tests, the default behavior of the test utility is to find all the test cases (that is, subclasses of `unittest.TestCase`) in any file whose name begins with `test`, automatically build a test suite out of those test cases, and run that suite. For more details about `unittest`, see the Python documentation. Warning If your tests rely on database access such as creating or querying models, be sure to create your test classes as subclasses of `django.test.TestCase` rather than `unittest.TestCase`. Using `unittest.TestCase` avoids the cost of running each test in a transaction and flushing the database, but if your tests interact with the database their behavior will vary based on the order that the test runner executes them. This can lead to unit tests that pass when run in isolation but fail when run in a suite. ## Running tests Once you’ve written tests, run them using the test command of your project’s `manage.py` utility: ~~~ $ ./manage.py test ~~~ Test discovery is based on the unittest module’s built-in test discovery. By default, this will discover tests in any file named “test*.py” under the current working directory. You can specify particular tests to run by supplying any number of “test labels” to `./manage.py test`. Each test label can be a full Python dotted path to a package, module, `TestCase` subclass, or test method. For instance: ~~~ # Run all the tests in the animals.tests module $ ./manage.py test animals.tests # Run all the tests found within the 'animals' package $ ./manage.py test animals # Run just one test case $ ./manage.py test animals.tests.AnimalTestCase # Run just one test method $ ./manage.py test animals.tests.AnimalTestCase.test_animals_can_speak ~~~ You can also provide a path to a directory to discover tests below that directory: ~~~ $ ./manage.py test animals/ ~~~ You can specify a custom filename pattern match using the `-p` (or `--pattern`) option, if your test files are named differently from the `test*.py` pattern: ~~~ $ ./manage.py test --pattern="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 `--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. 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. ### 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. You can prevent the test databases from being destroyed by adding the `--keepdb` flag to the test command. This will preserve the test database between runs. If the database does not exist, it will first be created. Any migrations will also be applied in order to keep it up to date. By default the test databases get their names by prepending `test_` to the value of the `NAME` settings for the databases defined in `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 `NAME <TEST_NAME>` in the `TEST <DATABASE-TEST>` dictionary for any given database in `DATABASES`. On PostgreSQL, `USER` will also need read access to the built-in `postgres` database. Aside from using a separate database, the test runner will otherwise use all of the same database settings you have in your settings file: `ENGINE <DATABASE-ENGINE>`, `USER`, `HOST`, etc. The test database is created by the user specified by `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 `CHARSET <TEST_CHARSET>`TEST option. If you’re using MySQL, you can also use the `COLLATION <TEST_COLLATION>` option to control the particular collation used by the test database. See the settings documentation for details of these and other advanced settings. If using a SQLite in-memory database with Python 3.4+ and SQLite 3.7.13+, shared cache will be enabled, so you can write tests with ability to share the database between threads. Finding data from your production database when running tests? If your code attempts to access the database when its modules are compiled, this will occur *before* the test database is set up, with potentially unexpected results. For example, if you have a database query in module-level code and a real database exists, production data could pollute your tests. *It is a bad idea to have such import-time database queries in your code* anyway – rewrite your code so that it doesn’t do this. This also applies to customized implementations of `ready()`. ### 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: * All `TestCase` subclasses are run first. * Then, all other Django-based tests (test cases based on `SimpleTestCase`, including `TransactionTestCase`) are run with no particular ordering guaranteed nor enforced among them. * Then any other `unittest.TestCase` tests (including doctests) that may alter the database without restoring it to its original state are run. 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 `TransactionTestCase` test, they must be updated to be able to run independently. You may reverse the execution order inside groups by passing `--reverse` to the test command. This can help with ensuring your tests are independent from each other. ### Rollback emulation Any initial data loaded in migrations will only be available in `TestCase` tests and not in `TransactionTestCase`tests, and additionally only on backends where transactions are supported (the most important exception being MyISAM). This is also true for tests which rely on `TransactionTestCase` such as `LiveServerTestCase` and`StaticLiveServerTestCase`. Django can reload that data for you on a per-testcase basis by setting the `serialized_rollback` option to `True`in the body of the `TestCase` or `TransactionTestCase`, but note that this will slow down that test suite by approximately 3x. Third-party apps or those developing against MyISAM will need to set this; in general, however, you should be developing your own projects against a transactional database and be using `TestCase` for most tests, and thus not need this setting. The initial serialization is usually very quick, but if you wish to exclude some apps from this process (and speed up test runs slightly), you may add those apps to `TEST_NON_SERIALIZED_APPS`. ### Other test conditions Regardless of the value of the `DEBUG` setting in your configuration file, all Django tests run with`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. ### 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 ~~~ 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: test_was_published_recently_with_future_poll (polls.tests.PollMethodTests) ---------------------------------------------------------------------- Traceback (most recent call last): File "/dev/mysite/polls/tests.py", line 16, in test_was_published_recently_with_future_poll self.assertEqual(future_poll.was_published_recently(), False) AssertionError: True != False ---------------------------------------------------------------------- Ran 1 test in 0.003s 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 `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 `PASSWORD_HASHERS`setting to a faster hashing algorithm: ~~~ PASSWORD_HASHERS = [ 'django.contrib.auth.hashers.MD5PasswordHasher', ] ~~~ Don’t forget to also include in `PASSWORD_HASHERS` any hashing algorithm used in fixtures, if any. ## 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](http://seleniumhq.org/) 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](http://seleniumhq.org/) 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 '<!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('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 `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*) 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*) 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](http://www.w3.org/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*) 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. 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*) 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*) 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*) 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*) 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*) Makes an 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*) 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 2616](https://tools.ietf.org/html/rfc2616.html), which mandates that TRACE requests should not have an entity-body. The `follow`, `secure`, and `extra` arguments act the same as for `Client.get()`. `login`(***credentials*) 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. `logout`() 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 string. 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' ~~~ `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. See [RFC 2616#section-10](https://tools.ietf.org/html/rfc2616.html#section-10) for a full list of HTTP status codes. `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'`.) `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']`. #### EXCEPTIONS 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() ~~~ #### EXAMPLE 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: #### SIMPLETESTCASE *class *`SimpleTestCase` A thin subclass of `unittest.TestCase`, it extends it with some basic functionality like: * Saving and restoring the Python warning machinery state. * Some useful assertions like: * Checking that a callable `raises a certain exception`. * Testing form field `rendering and error treatment`. * Testing `HTML responses for the presence/lack of a given fragment`. * Verifying that a template `has/hasn't been used to generate a given response content`. * Verifying a HTTP `redirect` is performed by the app. * Robustly testing two `HTML fragments` for equality/inequality or `containment`. * Robustly testing two `XML fragments` for equality/inequality. * Robustly testing two `JSON fragments` for equality. * The ability to run tests with modified settings. * Using the `client` `Client`. * Custom test-time `URL maps`. If you need any of the other more complex and heavyweight Django-specific features like: * Testing or using the ORM. * Database `fixtures`. * Test skipping based on database backend features. * The remaining specialized `assert*` methods. then you should use `TransactionTestCase` or `TestCase` instead. `SimpleTestCase` inherits from `unittest.TestCase`. 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(cls, MyTestCase).setUpClass() # Call parent first ... @classmethod def tearDownClass(cls): ... super(cls, MyTestCase).tearDownClass() # Call parent last ~~~ #### TRANSACTIONTESTCASE *class *`TransactionTestCase` Django’s `TestCase` class (described below) 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`. In older versions of Django, the effects of transaction commit and rollback could not be tested within a`TestCase`. With the completion of the deprecation cycle of the old-style transaction management in Django 1.8, transaction management commands (e.g. `transaction.commit()`) are no longer disabled within `TestCase`. `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. `TransactionTestCase` inherits from `SimpleTestCase`. #### TESTCASE *class *`TestCase` This class provides some additional capabilities that can be useful for testing Web sites. Converting a normal `unittest.TestCase` to a Django `TestCase` is easy: Just change the base class of your test from `'unittest.TestCase'` to `'django.test.TestCase'`. All of the standard Python unit test functionality will continue to be available, but it will be augmented with some useful additions, including: * Automatic loading of fixtures. * Wraps the tests within two nested `atomic` blocks: one for the whole class and one for each test. * Creates a TestClient instance. * Django-specific assertions for testing for things like redirection and form errors. *classmethod *`TestCase.``setUpTestData`() The class-level `atomic` block described above allows the creation of initial data at the class level, once for the whole `TestCase`. This technique allows for faster tests as compared to using `setUp()`. For example: ~~~ from django.test import TestCase class MyTests(TestCase): @classmethod def setUpTestData(cls): # Set up data for the whole TestCase cls.foo = Foo.objects.create(bar="Test") ... def test1(self): # Some test using self.foo ... def test2(self): # Some other test using self.foo ... ~~~ Note that if the tests are run on a database with no transaction support (for instance, MySQL with the MyISAM engine), `setUpTestData()` will be called before each test, negating the speed benefits. Warning If you want to test some specific database transaction behavior, you should use `TransactionTestCase`, as`TestCase` wraps test execution within an `atomic()` block. `TestCase` inherits from `TransactionTestCase`. #### LIVESERVERTESTCASE *class *`LiveServerTestCase` `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](http://seleniumhq.org/) 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 test command via the `--liveserver`option, for example: ~~~ ./manage.py test --liveserver=localhost:8082 ~~~ Another way of changing the default server address is by setting the DJANGO_LIVE_TEST_SERVER_ADDRESSenvironment variable somewhere in your code (for example, in a custom test runner): ~~~ 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](http://en.wikipedia.org/wiki/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: ~~~ ./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. To demonstrate how to use `LiveServerTestCase`, let’s write a simple Selenium test. First of all, you need to install the [selenium package](https://pypi.python.org/pypi/selenium) into your Python path: ~~~ 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: ~~~ from django.test import LiveServerTestCase from selenium.webdriver.firefox.webdriver import WebDriver class MySeleniumTests(LiveServerTestCase): fixtures = ['user-data.json'] @classmethod def setUpClass(cls): super(MySeleniumTests, cls).setUpClass() cls.selenium = WebDriver() @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: ~~~ ./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](http://selenium-python.readthedocs.org/en/latest/api.html) for more details. Tip If you use the `staticfiles` app in your project and need to perform live testing, then you might want to use the `StaticLiveServerTestCase` subclass which transparently serves all the assets during execution of its tests in a way very similar to what we get at development time with `DEBUG=True`, i.e. without having to collect them using `collectstatic`. 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](http://code.google.com/p/selenium/wiki/FrequentlyAskedQuestions#Q:_WebDriver_fails_to_find_elements_/_Does_not_block_on_page_loa) and [Selenium documentation](http://seleniumhq.org/docs/04_webdriver_advanced.html#explicit-waits) 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 TestCase, Client 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 Web site isn’t much use if there isn’t any data in the database. To make it easy to put test data into the database, Django’s custom `TransactionTestCase` class provides a way of loading 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 testFluffyAnimals(self): # A test that uses the fixtures. call_some_test_code() ~~~ Here’s specifically what will happen: * At the start of each test case, 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. This flush/load procedure is repeated for each test in the test case, so 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. #### 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. For example: ~~~ class TestMyViews(TestCase): multi_db = True def testIndexPageView(self): call_some_test_code() ~~~ This test case will flush *all* the test databases before running `testIndexPageView`. The `multi_db` flag also affects into which databases the attr: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`() 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](https://www.python.org/dev/peps/pep-0343)) 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`() 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_CLASSES={ '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`() In case you want to override a setting for a test method, Django provides the `override_settings()` decorator (see [PEP 318](https://www.python.org/dev/peps/pep-0318)). 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`() Likewise, Django provides the `modify_settings()` decorator: ~~~ from django.test import TestCase, modify_settings class MiddlewareTestCase(TestCase): @modify_settings(MIDDLEWARE_CLASSES={ '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_CLASSES={ '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 | Default file storage | #### 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](http://masteringdjango.com/testing-in-django/#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 an failure in your test suite. `SimpleTestCase.``assertRaisesMessage`(*expected_exception*, *expected_message*, *callable_obj=None*, **args*,***kwargs*) Asserts that execution of callable `callable_obj` raised the `expected_exception` exception and that such exception has an `expected_message` representation. Any other outcome is reported as a failure. Similar to unittest’s `assertRaisesRegex()` with the difference that `expected_message` isn’t a regular expression. `SimpleTestCase.``assertFieldOutput`(*fieldclass*, *valid*, *invalid*, *field_args=None*, *field_kwargs=None*,*empty_value=”*) 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=”*) 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=”*) 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*) 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*) Asserts that a `Response` instance produced the given `status_code` and that `text` does not appears 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*) 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=”*) 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*,*host=None*, *msg_prefix=”*, *fetch_redirect_response=True*) 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. The `host` argument sets a default host if `expected_url` doesn’t include one (e.g. `"/bar/"`). If `expected_url` is an absolute URL that includes a host (e.g. `"http://testhost/bar/"`), the `host` parameter will be ignored. Note that the test client doesn’t support fetching external URLs, but the parameter may be useful if you are testing with a custom HTTP host (for example, initializing the test client with`Client(HTTP_HOST="testhost")`. If `fetch_redirect_response` is `False`, the final page won’t be loaded. Since the test client can’t fetch externals 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*) 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*) 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*) 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*) 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=”*) 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*) 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*) 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*) 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*) 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)) ~~~ You can also use this as a context manager: ~~~ with self.assertNumQueries(2): Person.objects.create(name="Aaron") Person.objects.create(name="Daniel") ~~~ ### 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 = [] ~~~ ### Management Commands Management commands can be tested with the `call_command()` function. The output can be redirected into a `StringIO` instance: ~~~ from django.core.management import call_command from django.test import TestCase from django.utils.six import StringIO class ClosepollTest(TestCase): def test_command_output(self): out = StringIO() call_command('closepoll', stdout=out) self.assertIn('Expected output', out.getvalue()) ~~~ ### Skipping tests 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. `django.test.``skipIfDBFeature`(**feature_name_strings*) Skip the decorated test or `TestCase` if all of the named database features are supported. For example, the following test will not be executed if the database supports transactions (e.g., it would*not* run under PostgreSQL, but it would under MySQL with MyISAM tables): ~~~ class MyTests(TestCase): @skipIfDBFeature('supports_transactions') def test_transaction_behavior(self): # ... conditional test code ``skipIfDBFeature`` can accept multiple feature strings. ~~~ `django.test.``skipUnlessDBFeature`(**feature_name_strings*) Skip the decorated test or `TestCase` if any of the named database features are *not* supported. For example, the following test will only be executed if the database supports transactions (e.g., it would run under PostgreSQL, but *not* under MySQL with MyISAM tables): ~~~ class MyTests(TestCase): @skipUnlessDBFeature('supports_transactions') def test_transaction_behavior(self): # ... conditional test code ``skipUnlessDBFeature`` can accept multiple feature strings. ~~~ ## Using the Django test runner to test reusable applications If you are writing a reusable application you may want to use the Django test runner to run your own test suite and thus benefit from the Django testing infrastructure. A common practice is a *tests* directory next to the application code, with the following structure: ~~~ runtests.py polls/ __init__.py models.py ... tests/ __init__.py models.py test_settings.py tests.py ~~~ Let’s take a look inside a couple of those files: ~~~ # runtests.py #!/usr/bin/env python import os import sys import django from django.conf import settings from django.test.utils import get_runner if __name__ == "__main__": os.environ['DJANGO_SETTINGS_MODULE'] = 'tests.test_settings' django.setup() TestRunner = get_runner(settings) test_runner = TestRunner() failures = test_runner.run_tests(["tests"]) sys.exit(bool(failures)) ~~~ This is the script that you invoke to run the test suite. It sets up the Django environment, creates the test database and runs the tests. For the sake of clarity, this example contains only the bare minimum necessary to use the Django test runner. You may want to add command-line options for controlling verbosity, passing in specific test labels to run, etc. ~~~ # tests/test_settings.py SECRET_KEY = 'fake-key' INSTALLED_APPS = [ "tests", ] ~~~ This file contains the Django settings required to run your app’s tests. Again, this is a minimal example; your tests may require additional settings to run. Since the *tests* package is included in `INSTALLED_APPS` when running your tests, you can define test-only models in its `models.py` file. ## Using different testing frameworks Clearly, `unittest` is not the only Python testing framework. 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 `TEST_RUNNER` setting to determine what to do. By default,““TEST_RUNNER“ points to `'django.test.runner.DiscoverRunner'`. This class defines the default Django testing behavior. This behavior involves: 1. Performing global pre-test setup. 2. Looking for tests in any file below the current directory whose name matches the pattern `test*.py`. 3. Creating the test databases. 4. Running `migrate` to install models and initial data into the test databases. 5. Running the tests that were found. 6. Destroying the test databases. 7. Performing global post-test teardown. If you define your own test runner class and point `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. ### Defining a test runner A test runner is a class defining a `run_tests()` method. Django ships with a `DiscoverRunner` 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 *`django.test.runner.``DiscoverRunner`(*pattern=’test*.py’*, *top_level=None*, *verbosity=1*, *interactive=True*,*failfast=True*, *keepdb=False*, *reverse=False*, *debug_sql=False*, ***kwargs*) `DiscoverRunner` will search for tests in any file matching `pattern`. `top_level` can be used to specify the directory containing your top-level Python modules. Usually Django can figure this out automatically, so it’s not necessary to specify this option. If specified, it should generally be the directory containing your `manage.py` file. `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. If `keepdb` is `True`, the test suite will use the existing database, or create one if necessary. If `False`, a new database will be created, prompting the user to remove the existing one, if present. If `reverse` is `True`, test cases will be executed in the opposite order. This could be useful to debug tests that aren’t properly isolated and have side effects. Grouping by test class is preserved when using this option. If `debug_sql` is `True`, failing test cases will output SQL queries logged to the django.db.backends logger as well as the traceback. If `verbosity` is `2`, then queries in all tests are output. Django may, 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 `DiscoverRunner` or write your own test runner, ensure it accepts `**kwargs`. Your test runner may also define additional command-line options. Create or override an`add_arguments(cls, parser)` class method and add custom arguments by calling `parser.add_argument()` inside the method, so that the `test` command will be able to use those arguments. #### ATTRIBUTES `DiscoverRunner.``test_suite` The class used to build the test suite. By default it is set to `unittest.TestSuite`. This can be overridden if you wish to implement different logic for collecting tests. `DiscoverRunner.``test_runner` This is the class of the low-level test runner which is used to execute the individual tests and format the results. By default it is set to `unittest.TextTestRunner`. Despite the unfortunate similarity in naming conventions, this is not the same type of class as `DiscoverRunner`, which covers a broader set of responsibilities. You can override this attribute to modify the way tests are run and reported. `DiscoverRunner.``test_loader` This is the class that loads tests, whether from TestCases or modules or otherwise and bundles them into test suites for the runner to execute. By default it is set to `unittest.defaultTestLoader`. You can override this attribute if your tests are going to be loaded in unusual ways. #### METHODS `DiscoverRunner.``run_tests`(*test_labels*, *extra_tests=None*, ***kwargs*) Run the test suite. `test_labels` allows you to specify which tests to run and supports several formats (see`DiscoverRunner.build_suite()` for a list of supported formats). `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. *classmethod *`DiscoverRunner.``add_arguments`(*parser*) Override this class method to add custom arguments accepted by the `test` management command. See`argparse.ArgumentParser.add_argument()` for details about adding arguments to a parser. `DiscoverRunner.``setup_test_environment`(***kwargs*) Sets up the test environment by calling `setup_test_environment()` and setting `DEBUG` to `False`. `DiscoverRunner.``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 four forms: * `path.to.test_module.TestCase.test_method` – Run a single test method in a test case. * `path.to.test_module.TestCase` – Run all the test methods in a test case. * `path.to.module` – Search for and run all tests in the named Python package or module. * `path/to/directory` – Search for and run all tests below the named directory. If `test_labels` has a value of `None`, the test runner will search for tests in all files below the current directory whose names match its `pattern` (see above). `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. `DiscoverRunner.``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. `DiscoverRunner.``run_suite`(*suite*, ***kwargs*) Runs the test suite. Returns the result produced by the running the test suite. `DiscoverRunner.``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. `DiscoverRunner.``teardown_test_environment`(***kwargs*) Restores the pre-test environment. `DiscoverRunner.``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 #### DJANGO.TEST.UTILS To assist in the creation of your own test runner, Django provides a number of utility methods in the`django.test.utils` module. `django.test.utils.``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. `django.test.utils.``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. #### DJANGO.DB.CONNECTION.CREATION The creation module of the database backend also provides some utilities that can be useful during testing. `django.db.connection.creation.``create_test_db`([*verbosity=1*, *autoclobber=False*, *serialize=True*,*keepdb=False*]) Creates a new test database and runs `migrate` 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. `serialize` determines if Django serializes the database into an in-memory JSON string before running tests (used to restore the database state between tests if you don’t have transactions). You can set this to `False`to speed up creation time if you don’t have any test classes with serialized_rollback=True. If you are using the default test runner, you can control this with the the `SERIALIZE <TEST_SERIALIZE>` entry in the `TEST` `keepdb` determines if the test run should use an existing database, or create a new one. If `True`, the existing database will be used, or created if not present. If `False`, a new database will be created, prompting the user to remove the existing one, if present. Returns the name of the test database that it created. `create_test_db()` has the side effect of modifying the value of `NAME` in `DATABASES` to match the name of the test database. `django.db.connection.creation.``destroy_test_db`(*old_database_name*[, *verbosity=1*, *keepdb=False*]) Destroys the database whose name is the value of `NAME` in `DATABASES`, and sets `NAME` to the value of`old_database_name`. The `verbosity` argument has the same behavior as for `DiscoverRunner`. If the `keepdb` argument is `True`, then the connection to the database will be closed, but the database will not be destroyed.