Fixed #31224 -- Added support for asynchronous views and middleware.

This implements support for asynchronous views, asynchronous tests,
asynchronous middleware, and an asynchronous test client.

django/test/__init__.py

@@ -1,6 +1,8 @@
 """Django Unit Test framework."""
 
-from django.test.client import Client, RequestFactory
+from django.test.client import (
+    AsyncClient, AsyncRequestFactory, Client, RequestFactory,
+)
 from django.test.testcases import (
     LiveServerTestCase, SimpleTestCase, TestCase, TransactionTestCase,
     skipIfDBFeature, skipUnlessAnyDBFeature, skipUnlessDBFeature,
@@ -11,8 +13,9 @@ from django.test.utils import (
 )
 
 __all__ = [
-    'Client', 'RequestFactory', 'TestCase', 'TransactionTestCase',
-    'SimpleTestCase', 'LiveServerTestCase', 'skipIfDBFeature',
-    'skipUnlessAnyDBFeature', 'skipUnlessDBFeature', 'ignore_warnings',
-    'modify_settings', 'override_settings', 'override_system_checks', 'tag',
+    'AsyncClient', 'AsyncRequestFactory', 'Client', 'RequestFactory',
+    'TestCase', 'TransactionTestCase', 'SimpleTestCase', 'LiveServerTestCase',
+    'skipIfDBFeature', 'skipUnlessAnyDBFeature', 'skipUnlessDBFeature',
+    'ignore_warnings', 'modify_settings', 'override_settings',
+    'override_system_checks', 'tag',
 ]

django/test/client.py

@@ -9,7 +9,10 @@ from importlib import import_module
 from io import BytesIO
 from urllib.parse import unquote_to_bytes, urljoin, urlparse, urlsplit
 
+from asgiref.sync import sync_to_async
+
 from django.conf import settings
+from django.core.handlers.asgi import ASGIRequest
 from django.core.handlers.base import BaseHandler
 from django.core.handlers.wsgi import WSGIRequest
 from django.core.serializers.json import DjangoJSONEncoder
@@ -157,6 +160,52 @@ class ClientHandler(BaseHandler):
         return response
 
 
+class AsyncClientHandler(BaseHandler):
+    """An async version of ClientHandler."""
+    def __init__(self, enforce_csrf_checks=True, *args, **kwargs):
+        self.enforce_csrf_checks = enforce_csrf_checks
+        super().__init__(*args, **kwargs)
+
+    async def __call__(self, scope):
+        # Set up middleware if needed. We couldn't do this earlier, because
+        # settings weren't available.
+        if self._middleware_chain is None:
+            self.load_middleware(is_async=True)
+        # Extract body file from the scope, if provided.
+        if '_body_file' in scope:
+            body_file = scope.pop('_body_file')
+        else:
+            body_file = FakePayload('')
+
+        request_started.disconnect(close_old_connections)
+        await sync_to_async(request_started.send)(sender=self.__class__, scope=scope)
+        request_started.connect(close_old_connections)
+        request = ASGIRequest(scope, body_file)
+        # Sneaky little hack so that we can easily get round
+        # CsrfViewMiddleware. This makes life easier, and is probably required
+        # for backwards compatibility with external tests against admin views.
+        request._dont_enforce_csrf_checks = not self.enforce_csrf_checks
+        # Request goes through middleware.
+        response = await self.get_response_async(request)
+        # Simulate behaviors of most Web servers.
+        conditional_content_removal(request, response)
+        # Attach the originating ASGI request to the response so that it could
+        # be later retrieved.
+        response.asgi_request = request
+        # Emulate a server by calling the close method on completion.
+        if response.streaming:
+            response.streaming_content = await sync_to_async(closing_iterator_wrapper)(
+                response.streaming_content,
+                response.close,
+            )
+        else:
+            request_finished.disconnect(close_old_connections)
+            # Will fire request_finished.
+            await sync_to_async(response.close)()
+            request_finished.connect(close_old_connections)
+        return response
+
+
 def store_rendered_templates(store, signal, sender, template, context, **kwargs):
     """
     Store templates and contexts that are rendered.
@@ -421,7 +470,194 @@ class RequestFactory:
         return self.request(**r)
 
 
-class Client(RequestFactory):
+class AsyncRequestFactory(RequestFactory):
+    """
+    Class that lets you create mock ASGI-like Request objects for use in
+    testing. Usage:
+
+    rf = AsyncRequestFactory()
+    get_request = await rf.get('/hello/')
+    post_request = await rf.post('/submit/', {'foo': 'bar'})
+
+    Once you have a request object you can pass it to any view function,
+    including synchronous ones. The reason we have a separate class here is:
+    a) this makes ASGIRequest subclasses, and
+    b) AsyncTestClient can subclass it.
+    """
+    def _base_scope(self, **request):
+        """The base scope for a request."""
+        # This is a minimal valid ASGI scope, plus:
+        # - headers['cookie'] for cookie support,
+        # - 'client' often useful, see #8551.
+        scope = {
+            'asgi': {'version': '3.0'},
+            'type': 'http',
+            'http_version': '1.1',
+            'client': ['127.0.0.1', 0],
+            'server': ('testserver', '80'),
+            'scheme': 'http',
+            'method': 'GET',
+            'headers': [],
+            **self.defaults,
+            **request,
+        }
+        scope['headers'].append((
+            b'cookie',
+            b'; '.join(sorted(
+                ('%s=%s' % (morsel.key, morsel.coded_value)).encode('ascii')
+                for morsel in self.cookies.values()
+            )),
+        ))
+        return scope
+
+    def request(self, **request):
+        """Construct a generic request object."""
+        # This is synchronous, which means all methods on this class are.
+        # AsyncClient, however, has an async request function, which makes all
+        # its methods async.
+        if '_body_file' in request:
+            body_file = request.pop('_body_file')
+        else:
+            body_file = FakePayload('')
+        return ASGIRequest(self._base_scope(**request), body_file)
+
+    def generic(
+        self, method, path, data='', content_type='application/octet-stream',
+        secure=False, **extra,
+    ):
+        """Construct an arbitrary HTTP request."""
+        parsed = urlparse(str(path))  # path can be lazy.
+        data = force_bytes(data, settings.DEFAULT_CHARSET)
+        s = {
+            'method': method,
+            'path': self._get_path(parsed),
+            'server': ('127.0.0.1', '443' if secure else '80'),
+            'scheme': 'https' if secure else 'http',
+            'headers': [(b'host', b'testserver')],
+        }
+        if data:
+            s['headers'].extend([
+                (b'content-length', bytes(len(data))),
+                (b'content-type', content_type.encode('ascii')),
+            ])
+            s['_body_file'] = FakePayload(data)
+        s.update(extra)
+        # If QUERY_STRING is absent or empty, we want to extract it from the
+        # URL.
+        if not s.get('query_string'):
+            s['query_string'] = parsed[4]
+        return self.request(**s)
+
+
+class ClientMixin:
+    """
+    Mixin with common methods between Client and AsyncClient.
+    """
+    def store_exc_info(self, **kwargs):
+        """Store exceptions when they are generated by a view."""
+        self.exc_info = sys.exc_info()
+
+    def check_exception(self, response):
+        """
+        Look for a signaled exception, clear the current context exception
+        data, re-raise the signaled exception, and clear the signaled exception
+        from the local cache.
+        """
+        response.exc_info = self.exc_info
+        if self.exc_info:
+            _, exc_value, _ = self.exc_info
+            self.exc_info = None
+            if self.raise_request_exception:
+                raise exc_value
+
+    @property
+    def session(self):
+        """Return the current session variables."""
+        engine = import_module(settings.SESSION_ENGINE)
+        cookie = self.cookies.get(settings.SESSION_COOKIE_NAME)
+        if cookie:
+            return engine.SessionStore(cookie.value)
+        session = engine.SessionStore()
+        session.save()
+        self.cookies[settings.SESSION_COOKIE_NAME] = session.session_key
+        return session
+
+    def login(self, **credentials):
+        """
+        Set the Factory to appear as if it has successfully logged into a site.
+
+        Return True if login is possible or False if the provided credentials
+        are incorrect.
+        """
+        from django.contrib.auth import authenticate
+        user = authenticate(**credentials)
+        if user:
+            self._login(user)
+            return True
+        return False
+
+    def force_login(self, user, backend=None):
+        def get_backend():
+            from django.contrib.auth import load_backend
+            for backend_path in settings.AUTHENTICATION_BACKENDS:
+                backend = load_backend(backend_path)
+                if hasattr(backend, 'get_user'):
+                    return backend_path
+
+        if backend is None:
+            backend = get_backend()
+        user.backend = backend
+        self._login(user, backend)
+
+    def _login(self, user, backend=None):
+        from django.contrib.auth import login
+        # Create a fake request to store login details.
+        request = HttpRequest()
+        if self.session:
+            request.session = self.session
+        else:
+            engine = import_module(settings.SESSION_ENGINE)
+            request.session = engine.SessionStore()
+        login(request, user, backend)
+        # Save the session values.
+        request.session.save()
+        # Set the cookie to represent the session.
+        session_cookie = settings.SESSION_COOKIE_NAME
+        self.cookies[session_cookie] = request.session.session_key
+        cookie_data = {
+            'max-age': None,
+            'path': '/',
+            'domain': settings.SESSION_COOKIE_DOMAIN,
+            'secure': settings.SESSION_COOKIE_SECURE or None,
+            'expires': None,
+        }
+        self.cookies[session_cookie].update(cookie_data)
+
+    def logout(self):
+        """Log out the user by removing the cookies and session object."""
+        from django.contrib.auth import get_user, logout
+        request = HttpRequest()
+        if self.session:
+            request.session = self.session
+            request.user = get_user(request)
+        else:
+            engine = import_module(settings.SESSION_ENGINE)
+            request.session = engine.SessionStore()
+        logout(request)
+        self.cookies = SimpleCookie()
+
+    def _parse_json(self, response, **extra):
+        if not hasattr(response, '_json'):
+            if not JSON_CONTENT_TYPE_RE.match(response.get('Content-Type')):
+                raise ValueError(
+                    'Content-Type header is "%s", not "application/json"'
+                    % response.get('Content-Type')
+                )
+            response._json = json.loads(response.content.decode(response.charset), **extra)
+        return response._json
+
+
+class Client(ClientMixin, RequestFactory):
     """
     A class that can act as a client for testing purposes.
 
@@ -446,23 +682,6 @@ class Client(RequestFactory):
         self.exc_info = None
         self.extra = None
 
-    def store_exc_info(self, **kwargs):
-        """Store exceptions when they are generated by a view."""
-        self.exc_info = sys.exc_info()
-
-    @property
-    def session(self):
-        """Return the current session variables."""
-        engine = import_module(settings.SESSION_ENGINE)
-        cookie = self.cookies.get(settings.SESSION_COOKIE_NAME)
-        if cookie:
-            return engine.SessionStore(cookie.value)
-
-        session = engine.SessionStore()
-        session.save()
-        self.cookies[settings.SESSION_COOKIE_NAME] = session.session_key
-        return session
-
     def request(self, **request):
         """
         The master request method. Compose the environment dictionary and pass
@@ -486,15 +705,8 @@ class Client(RequestFactory):
         finally:
             signals.template_rendered.disconnect(dispatch_uid=signal_uid)
             got_request_exception.disconnect(dispatch_uid=exception_uid)
-        # Look for a signaled exception, clear the current context exception
-        # data, then re-raise the signaled exception. Also clear the signaled
-        # exception from the local cache.
-        response.exc_info = self.exc_info
-        if self.exc_info:
-            _, exc_value, _ = self.exc_info
-            self.exc_info = None
-            if self.raise_request_exception:
-                raise exc_value
+        # Check for signaled exceptions.
+        self.check_exception(response)
         # Save the client and request that stimulated the response.
         response.client = self
         response.request = request
@@ -583,85 +795,6 @@ class Client(RequestFactory):
             response = self._handle_redirects(response, data=data, **extra)
         return response
 
-    def login(self, **credentials):
-        """
-        Set the Factory to appear as if it has successfully logged into a site.
-
-        Return True if login is possible; False if the provided credentials
-        are incorrect.
-        """
-        from django.contrib.auth import authenticate
-        user = authenticate(**credentials)
-        if user:
-            self._login(user)
-            return True
-        else:
-            return False
-
-    def force_login(self, user, backend=None):
-        def get_backend():
-            from django.contrib.auth import load_backend
-            for backend_path in settings.AUTHENTICATION_BACKENDS:
-                backend = load_backend(backend_path)
-                if hasattr(backend, 'get_user'):
-                    return backend_path
-        if backend is None:
-            backend = get_backend()
-        user.backend = backend
-        self._login(user, backend)
-
-    def _login(self, user, backend=None):
-        from django.contrib.auth import login
-        engine = import_module(settings.SESSION_ENGINE)
-
-        # Create a fake request to store login details.
-        request = HttpRequest()
-
-        if self.session:
-            request.session = self.session
-        else:
-            request.session = engine.SessionStore()
-        login(request, user, backend)
-
-        # Save the session values.
-        request.session.save()
-
-        # Set the cookie to represent the session.
-        session_cookie = settings.SESSION_COOKIE_NAME
-        self.cookies[session_cookie] = request.session.session_key
-        cookie_data = {
-            'max-age': None,
-            'path': '/',
-            'domain': settings.SESSION_COOKIE_DOMAIN,
-            'secure': settings.SESSION_COOKIE_SECURE or None,
-            'expires': None,
-        }
-        self.cookies[session_cookie].update(cookie_data)
-
-    def logout(self):
-        """Log out the user by removing the cookies and session object."""
-        from django.contrib.auth import get_user, logout
-
-        request = HttpRequest()
-        engine = import_module(settings.SESSION_ENGINE)
-        if self.session:
-            request.session = self.session
-            request.user = get_user(request)
-        else:
-            request.session = engine.SessionStore()
-        logout(request)
-        self.cookies = SimpleCookie()
-
-    def _parse_json(self, response, **extra):
-        if not hasattr(response, '_json'):
-            if not JSON_CONTENT_TYPE_RE.match(response.get('Content-Type')):
-                raise ValueError(
-                    'Content-Type header is "{}", not "application/json"'
-                    .format(response.get('Content-Type'))
-                )
-            response._json = json.loads(response.content.decode(response.charset), **extra)
-        return response._json
-
     def _handle_redirects(self, response, data='', content_type='', **extra):
         """
         Follow any redirects by requesting responses from the server using GET.
@@ -714,3 +847,66 @@ class Client(RequestFactory):
                 raise RedirectCycleError("Too many redirects.", last_response=response)
 
         return response
+
+
+class AsyncClient(ClientMixin, AsyncRequestFactory):
+    """
+    An async version of Client that creates ASGIRequests and calls through an
+    async request path.
+
+    Does not currently support "follow" on its methods.
+    """
+    def __init__(self, enforce_csrf_checks=False, raise_request_exception=True, **defaults):
+        super().__init__(**defaults)
+        self.handler = AsyncClientHandler(enforce_csrf_checks)
+        self.raise_request_exception = raise_request_exception
+        self.exc_info = None
+        self.extra = None
+
+    async def request(self, **request):
+        """
+        The master request method. Compose the scope dictionary and pass to the
+        handler, return the result of the handler. Assume defaults for the
+        query environment, which can be overridden using the arguments to the
+        request.
+        """
+        if 'follow' in request:
+            raise NotImplementedError(
+                'AsyncClient request methods do not accept the follow '
+                'parameter.'
+            )
+        scope = self._base_scope(**request)
+        # Curry a data dictionary into an instance of the template renderer
+        # callback function.
+        data = {}
+        on_template_render = partial(store_rendered_templates, data)
+        signal_uid = 'template-render-%s' % id(request)
+        signals.template_rendered.connect(on_template_render, dispatch_uid=signal_uid)
+        # Capture exceptions created by the handler.
+        exception_uid = 'request-exception-%s' % id(request)
+        got_request_exception.connect(self.store_exc_info, dispatch_uid=exception_uid)
+        try:
+            response = await self.handler(scope)
+        finally:
+            signals.template_rendered.disconnect(dispatch_uid=signal_uid)
+            got_request_exception.disconnect(dispatch_uid=exception_uid)
+        # Check for signaled exceptions.
+        self.check_exception(response)
+        # Save the client and request that stimulated the response.
+        response.client = self
+        response.request = request
+        # Add any rendered template detail to the response.
+        response.templates = data.get('templates', [])
+        response.context = data.get('context')
+        response.json = partial(self._parse_json, response)
+        # Attach the ResolverMatch instance to the response.
+        response.resolver_match = SimpleLazyObject(lambda: resolve(request['path']))
+        # Flatten a single context. Not really necessary anymore thanks to the
+        # __getattr__ flattening in ContextList, but has some edge case
+        # backwards compatibility implications.
+        if response.context and len(response.context) == 1:
+            response.context = response.context[0]
+        # Update persistent cookie data.
+        if response.cookies:
+            self.cookies.update(response.cookies)
+        return response

django/test/testcases.py

@@ -33,7 +33,7 @@ from django.db import DEFAULT_DB_ALIAS, connection, connections, transaction
 from django.forms.fields import CharField
 from django.http import QueryDict
 from django.http.request import split_domain_port, validate_host
-from django.test.client import Client
+from django.test.client import AsyncClient, Client
 from django.test.html import HTMLParseError, parse_html
 from django.test.signals import setting_changed, template_rendered
 from django.test.utils import (
@@ -151,6 +151,7 @@ class SimpleTestCase(unittest.TestCase):
     # The class we'll use for the test client self.client.
     # Can be overridden in derived classes.
     client_class = Client
+    async_client_class = AsyncClient
     _overridden_settings = None
     _modified_settings = None
 
@@ -292,6 +293,7 @@ class SimpleTestCase(unittest.TestCase):
         * Clear the mail test outbox.
         """
         self.client = self.client_class()
+        self.async_client = self.async_client_class()
         mail.outbox = []
 
     def _post_teardown(self):

django/test/utils.py

@@ -1,3 +1,4 @@
+import asyncio
 import logging
 import re
 import sys
@@ -362,12 +363,22 @@ class TestContextDecorator:
         raise TypeError('Can only decorate subclasses of unittest.TestCase')
 
     def decorate_callable(self, func):
-        @wraps(func)
-        def inner(*args, **kwargs):
-            with self as context:
-                if self.kwarg_name:
-                    kwargs[self.kwarg_name] = context
-                return func(*args, **kwargs)
+        if asyncio.iscoroutinefunction(func):
+            # If the inner function is an async function, we must execute async
+            # as well so that the `with` statement executes at the right time.
+            @wraps(func)
+            async def inner(*args, **kwargs):
+                with self as context:
+                    if self.kwarg_name:
+                        kwargs[self.kwarg_name] = context
+                    return await func(*args, **kwargs)
+        else:
+            @wraps(func)
+            def inner(*args, **kwargs):
+                with self as context:
+                    if self.kwarg_name:
+                        kwargs[self.kwarg_name] = context
+                    return func(*args, **kwargs)
         return inner
 
     def __call__(self, decorated):