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test.py

# Testing

> Code without tests is broken as designed.

> — Jacob Kaplan-Moss

REST framework includes a few helper classes that extend Django's existing test framework, and improve support for making API requests.

# APIRequestFactory

Extends Django's existing `RequestFactory` class.

## Creating test requests

The `APIRequestFactory` class supports an almost identical API to Django's standard `RequestFactory` class. This means that the standard `.get()`, `.post()`, `.put()`, `.patch()`, `.delete()`, `.head()` and `.options()` methods are all available.

    from rest_framework.test import APIRequestFactory

    # Using the standard RequestFactory API to create a form POST request
    factory = APIRequestFactory()
    request = factory.post('/notes/', {'title': 'new idea'})

    # Using the standard RequestFactory API to encode JSON data
    request = factory.post('/notes/', {'title': 'new idea'}, content_type='application/json')

#### Using the `format` argument

Methods which create a request body, such as `post`, `put` and `patch`, include a `format` argument, which make it easy to generate requests using a wide set of request formats. When using this argument, the factory will select an appropriate renderer and its configured `content_type`. For example:

    # Create a JSON POST request
    factory = APIRequestFactory()
    request = factory.post('/notes/', {'title': 'new idea'}, format='json')

By default the available formats are `'multipart'` and `'json'`. For compatibility with Django's existing `RequestFactory` the default format is `'multipart'`.

To support a wider set of request formats, or change the default format, see the configuration section.

#### Explicitly encoding the request body

If you need to explicitly encode the request body, you can do so by setting the `content_type` flag. For example:

    request = factory.post('/notes/', yaml.dump({'title': 'new idea'}), content_type='application/yaml')

#### PUT and PATCH with form data

One difference worth noting between Django's `RequestFactory` and REST framework's `APIRequestFactory` is that multipart form data will be encoded for methods other than just `.post()`.

For example, using `APIRequestFactory`, you can make a form PUT request like so:

    factory = APIRequestFactory()
    request = factory.put('/notes/547/', {'title': 'remember to email dave'})

Using Django's `RequestFactory`, you'd need to explicitly encode the data yourself:

    from django.test.client import encode_multipart, RequestFactory

    factory = RequestFactory()
    data = {'title': 'remember to email dave'}
    content = encode_multipart('BoUnDaRyStRiNg', data)
    content_type = 'multipart/form-data; boundary=BoUnDaRyStRiNg'
    request = factory.put('/notes/547/', content, content_type=content_type)

## Forcing authentication

When testing views directly using a request factory, it's often convenient to be able to directly authenticate the request, rather than having to construct the correct authentication credentials.

To forcibly authenticate a request, use the `force_authenticate()` method.

    from rest_framework.test import force_authenticate

    factory = APIRequestFactory()
    user = User.objects.get(username='olivia')
    view = AccountDetail.as_view()

    # Make an authenticated request to the view...
    request = factory.get('/accounts/django-superstars/')
    force_authenticate(request, user=user)
    response = view(request)

The signature for the method is `force_authenticate(request, user=None, token=None)`. When making the call, either or both of the user and token may be set.

For example, when forcibly authenticating using a token, you might do something like the following:

    user = User.objects.get(username='olivia')
    request = factory.get('/accounts/django-superstars/')
    force_authenticate(request, user=user, token=user.auth_token)

Note: `force_authenticate` directly sets `request.user` to the in-memory `user` instance. If you are re-using the same `user` instance across multiple tests that update the saved `user` state, you may need to call `refresh_from_db()` between tests.

Note: When using `APIRequestFactory`, the object that is returned is Django's standard `HttpRequest`, and not REST framework's `Request` object, which is only generated once the view is called.

This means that setting attributes directly on the request object may not always have the effect you expect. For example, setting `.token` directly will have no effect, and setting `.user` directly will only work if session authentication is being used.

    # Request will only authenticate if `SessionAuthentication` is in use.
    request = factory.get('/accounts/django-superstars/')
    request.user = user
    response = view(request)

## Forcing CSRF validation

By default, requests created with `APIRequestFactory` will not have CSRF validation applied when passed to a REST framework view. If you need to explicitly turn CSRF validation on, you can do so by setting the `enforce_csrf_checks` flag when instantiating the factory.

    factory = APIRequestFactory(enforce_csrf_checks=True)

Note: It's worth noting that Django's standard `RequestFactory` doesn't need to include this option, because when using regular Django the CSRF validation takes place in middleware, which is not run when testing views directly. When using REST framework, CSRF validation takes place inside the view, so the request factory needs to disable view-level CSRF checks.

# APIClient

Extends Django's existing `Client` class.

## Making requests

The `APIClient` class supports the same request interface as Django's standard `Client` class. This means that the standard `.get()`, `.post()`, `.put()`, `.patch()`, `.delete()`, `.head()` and `.options()` methods are all available. For example:

    from rest_framework.test import APIClient

    client = APIClient()
    client.post('/notes/', {'title': 'new idea'}, format='json')

To support a wider set of request formats, or change the default format, see the configuration section.

## Authenticating

#### .login(**kwargs)

The `login` method functions exactly as it does with Django's regular `Client` class. This allows you to authenticate requests against any views which include `SessionAuthentication`.

    # Make all requests in the context of a logged in session.
    client = APIClient()
    client.login(username='lauren', password='secret')

To logout, call the `logout` method as usual.

    # Log out
    client.logout()

The `login` method is appropriate for testing APIs that use session authentication, for example web sites which include AJAX interaction with the API.

#### .credentials(**kwargs)

The `credentials` method can be used to set headers that will then be included on all subsequent requests by the test client.

    from rest_framework.authtoken.models import Token
    from rest_framework.test import APIClient

    # Include an appropriate `Authorization:` header on all requests.
    token = Token.objects.get(user__username='lauren')
    client = APIClient()
    client.credentials(HTTP_AUTHORIZATION='Token ' + token.key)

Note that calling `credentials` a second time overwrites any existing credentials. You can unset any existing credentials by calling the method with no arguments.

    # Stop including any credentials
    client.credentials()

The `credentials` method is appropriate for testing APIs that require authentication headers, such as basic authentication, OAuth1a and OAuth2 authentication, and simple token authentication schemes.

#### .force_authenticate(user=None, token=None)

Sometimes you may want to bypass authentication entirely and force all requests by the test client to be automatically treated as authenticated.

This can be a useful shortcut if you're testing the API but don't want to have to construct valid authentication credentials in order to make test requests.

    user = User.objects.get(username='lauren')
    client = APIClient()
    client.force_authenticate(user=user)

To unauthenticate subsequent requests, call `force_authenticate` setting the user and/or token to `None`.

    client.force_authenticate(user=None)

## CSRF validation

By default CSRF validation is not applied when using `APIClient`. If you need to explicitly enable CSRF validation, you can do so by setting the `enforce_csrf_checks` flag when instantiating the client.

    client = APIClient(enforce_csrf_checks=True)

As usual CSRF validation will only apply to any session authenticated views. This means CSRF validation will only occur if the client has been logged in by calling `login()`.

# RequestsClient

REST framework also includes a client for interacting with your application using the popular Python library, `requests`. This may be useful if:

- You are expecting to interface with the API primarily from another Python service, and want to test the service at the same level as the client will see.
- You want to write tests in such a way that they can also be run against a staging or live environment. (See "Live tests" below.)

This exposes exactly the same interface as if you were using a requests session directly.

    from rest_framework.test import RequestsClient

    client = RequestsClient()
    response = client.get('http://testserver/users/')
    assert response.status_code == 200

Note that the requests client requires you to pass fully qualified URLs.

## RequestsClient and working with the database

The `RequestsClient` class is useful if you want to write tests that solely interact with the service interface. This is a little stricter than using the standard Django test client, as it means that all interactions should be via the API.

If you're using `RequestsClient` you'll want to ensure that test setup, and results assertions are performed as regular API calls, rather than interacting with the database models directly. For example, rather than checking that `Customer.objects.count() == 3` you would list the customers endpoint, and ensure that it contains three records.

## Headers & Authentication

Custom headers and authentication credentials can be provided in the same way as when using a standard `requests.Session` instance.

    from requests.auth import HTTPBasicAuth

    client.auth = HTTPBasicAuth('user', 'pass')
    client.headers.update({'x-test': 'true'})

## CSRF

If you're using `SessionAuthentication` then you'll need to include a CSRF token for any `POST`, `PUT`, `PATCH` or `DELETE` requests.

You can do so by following the same flow that a JavaScript based client would use. First, make a `GET` request in order to obtain a CSRF token, then present that token in the following request.

For example...

    client = RequestsClient()

    # Obtain a CSRF token.
    response = client.get('http://testserver/homepage/')
    assert response.status_code == 200
    csrftoken = response.cookies['csrftoken']

    # Interact with the API.
    response = client.post('http://testserver/organisations/', json={
        'name': 'MegaCorp',
        'status': 'active'
    }, headers={'X-CSRFToken': csrftoken})
    assert response.status_code == 200

## Live tests

With careful usage both the `RequestsClient` and the `CoreAPIClient` provide the ability to write test cases that can run either in development, or be run directly against your staging server or production environment.

Using this style to create basic tests of a few core pieces of functionality is a powerful way to validate your live service. Doing so may require some careful attention to setup and teardown to ensure that the tests run in a way that they do not directly affect customer data.

# CoreAPIClient

The CoreAPIClient allows you to interact with your API using the Python `coreapi` client library.

    # Fetch the API schema
    client = CoreAPIClient()
    schema = client.get('http://testserver/schema/')

    # Create a new organisation
    params = {'name': 'MegaCorp', 'status': 'active'}
    client.action(schema, ['organisations', 'create'], params)

    # Ensure that the organisation exists in the listing
    data = client.action(schema, ['organisations', 'list'])
    assert(len(data) == 1)
    assert(data == [{'name': 'MegaCorp', 'status': 'active'}])

## Headers & Authentication

Custom headers and authentication may be used with `CoreAPIClient` in a similar way as with `RequestsClient`.

    from requests.auth import HTTPBasicAuth

    client = CoreAPIClient()
    client.session.auth = HTTPBasicAuth('user', 'pass')
    client.session.headers.update({'x-test': 'true'})

# API Test cases

REST framework includes the following test case classes, that mirror the existing Django's test case classes, but use `APIClient` instead of Django's default `Client`.

- `APISimpleTestCase`
- `APITransactionTestCase`
- `APITestCase`
- `APILiveServerTestCase`

## Example

You can use any of REST framework's test case classes as you would for the regular Django test case classes. The `self.client` attribute will be an `APIClient` instance.

    from django.urls import reverse
    from rest_framework import status
    from rest_framework.test import APITestCase
    from myproject.apps.core.models import Account

    class AccountTests(APITestCase):
        def test_create_account(self):
            """
            Ensure we can create a new account object.
            """
            url = reverse('account-list')
            data = {'name': 'DabApps'}
            response = self.client.post(url, data, format='json')
            self.assertEqual(response.status_code, status.HTTP_201_CREATED)
            self.assertEqual(Account.objects.count(), 1)
            self.assertEqual(Account.objects.get().name, 'DabApps')

# URLPatternsTestCase

REST framework also provides a test case class for isolating `urlpatterns` on a per-class basis. Note that this inherits from Django's `SimpleTestCase`, and will most likely need to be mixed with another test case class.

## Example

    from django.urls import include, path, reverse
    from rest_framework.test import APITestCase, URLPatternsTestCase

    class AccountTests(APITestCase, URLPatternsTestCase):
        urlpatterns = [
            path('api/', include('api.urls')),
        ]

        def test_create_account(self):
            """
            Ensure we can create a new account object.
            """
            url = reverse('account-list')
            response = self.client.get(url, format='json')
            self.assertEqual(response.status_code, status.HTTP_200_OK)
            self.assertEqual(len(response.data), 1)

# Testing responses

## Checking the response data

When checking the validity of test responses it's often more convenient to inspect the data that the response was created with, rather than inspecting the fully rendered response.

For example, it's easier to inspect `response.data`:

    response = self.client.get('/users/4/')
    self.assertEqual(response.data, {'id': 4, 'username': 'lauren'})

Instead of inspecting the result of parsing `response.content`:

    response = self.client.get('/users/4/')
    self.assertEqual(json.loads(response.content), {'id': 4, 'username': 'lauren'})

## Rendering responses

If you're testing views directly using `APIRequestFactory`, the responses that are returned will not yet be rendered, as rendering of template responses is performed by Django's internal request-response cycle. In order to access `response.content`, you'll first need to render the response.

    view = UserDetail.as_view()
    request = factory.get('/users/4')
    response = view(request, pk='4')
    response.render()  # Cannot access `response.content` without this.
    self.assertEqual(response.content, '{"username": "lauren", "id": 4}')

# Configuration

## Setting the default format

The default format used to make test requests may be set using the `TEST_REQUEST_DEFAULT_FORMAT` setting key. For example, to always use JSON for test requests by default instead of standard multipart form requests, set the following in your `settings.py` file:

    REST_FRAMEWORK = {
        ...
        'TEST_REQUEST_DEFAULT_FORMAT': 'json'
    }

## Setting the available formats

If you need to test requests using something other than multipart or json requests, you can do so by setting the `TEST_REQUEST_RENDERER_CLASSES` setting.

For example, to add support for using `format='html'` in test requests, you might have something like this in your `settings.py` file.

    REST_FRAMEWORK = {
        ...
        'TEST_REQUEST_RENDERER_CLASSES': [
            'rest_framework.renderers.MultiPartRenderer',
            'rest_framework.renderers.JSONRenderer',
            'rest_framework.renderers.TemplateHTMLRenderer'
        ]
    }