Fixed #30451 -- Added ASGI handler and coroutine-safety.

This adds an ASGI handler, asgi.py file for the default project layout,
a few async utilities and adds async-safety to many parts of Django.

9 files changed, 149 insertions, 9 deletions

diff --git a/tests/asgi/__init__.py b/tests/asgi/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/asgi/__init__.py
diff --git a/tests/asgi/tests.py b/tests/asgi/tests.py
new file mode 100644
index 0000000000..243e77defb
--- /dev/null
+++ b/tests/asgi/tests.py
@@ -0,0 +1,84 @@
+import sys
+
+from asgiref.sync import async_to_sync
+from asgiref.testing import ApplicationCommunicator
+
+from django.core.asgi import get_asgi_application
+from django.core.signals import request_started
+from django.db import close_old_connections
+from django.test import SimpleTestCase, override_settings
+
+from .urls import test_filename
+
+
+@override_settings(ROOT_URLCONF='asgi.urls')
+class ASGITest(SimpleTestCase):
+
+    def setUp(self):
+        request_started.disconnect(close_old_connections)
+
+    def _get_scope(self, **kwargs):
+        return {
+            'type': 'http',
+            'asgi': {'version': '3.0', 'spec_version': '2.1'},
+            'http_version': '1.1',
+            'method': 'GET',
+            'query_string': b'',
+            'server': ('testserver', 80),
+            **kwargs,
+        }
+
+    def tearDown(self):
+        request_started.connect(close_old_connections)
+
+    @async_to_sync
+    async def test_get_asgi_application(self):
+        """
+        get_asgi_application() returns a functioning ASGI callable.
+        """
+        application = get_asgi_application()
+        # Construct HTTP request.
+        communicator = ApplicationCommunicator(application, self._get_scope(path='/'))
+        await communicator.send_input({'type': 'http.request'})
+        # Read the response.
+        response_start = await communicator.receive_output()
+        self.assertEqual(response_start['type'], 'http.response.start')
+        self.assertEqual(response_start['status'], 200)
+        self.assertEqual(
+            set(response_start['headers']),
+            {
+                (b'Content-Length', b'12'),
+                (b'Content-Type', b'text/html; charset=utf-8'),
+            },
+        )
+        response_body = await communicator.receive_output()
+        self.assertEqual(response_body['type'], 'http.response.body')
+        self.assertEqual(response_body['body'], b'Hello World!')
+
+    @async_to_sync
+    async def test_file_response(self):
+        """
+        Makes sure that FileResponse works over ASGI.
+        """
+        application = get_asgi_application()
+        # Construct HTTP request.
+        communicator = ApplicationCommunicator(application, self._get_scope(path='/file/'))
+        await communicator.send_input({'type': 'http.request'})
+        # Get the file content.
+        with open(test_filename, 'rb') as test_file:
+            test_file_contents = test_file.read()
+        # Read the response.
+        response_start = await communicator.receive_output()
+        self.assertEqual(response_start['type'], 'http.response.start')
+        self.assertEqual(response_start['status'], 200)
+        self.assertEqual(
+            set(response_start['headers']),
+            {
+                (b'Content-Length', str(len(test_file_contents)).encode('ascii')),
+                (b'Content-Type', b'text/plain' if sys.platform.startswith('win') else b'text/x-python'),
+                (b'Content-Disposition', b'inline; filename="urls.py"'),
+            },
+        )
+        response_body = await communicator.receive_output()
+        self.assertEqual(response_body['type'], 'http.response.body')
+        self.assertEqual(response_body['body'], test_file_contents)
diff --git a/tests/asgi/urls.py b/tests/asgi/urls.py
new file mode 100644
index 0000000000..4177ec8c9a
--- /dev/null
+++ b/tests/asgi/urls.py
@@ -0,0 +1,15 @@
+from django.http import FileResponse, HttpResponse
+from django.urls import path
+
+
+def helloworld(request):
+    return HttpResponse('Hello World!')
+
+
+test_filename = __file__
+
+
+urlpatterns = [
+    path('', helloworld),
+    path('file/', lambda x: FileResponse(open(test_filename, 'rb'))),
+]
diff --git a/tests/async/__init__.py b/tests/async/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/async/__init__.py
diff --git a/tests/async/models.py b/tests/async/models.py
new file mode 100644
index 0000000000..0fd606b07e
--- /dev/null
+++ b/tests/async/models.py
@@ -0,0 +1,5 @@
+from django.db import models
+
+
+class SimpleModel(models.Model):
+    field = models.IntegerField()
diff --git a/tests/async/tests.py b/tests/async/tests.py
new file mode 100644
index 0000000000..1e1cabc1c6
--- /dev/null
+++ b/tests/async/tests.py
@@ -0,0 +1,36 @@
+from asgiref.sync import async_to_sync
+
+from django.core.exceptions import SynchronousOnlyOperation
+from django.test import SimpleTestCase
+from django.utils.asyncio import async_unsafe
+
+from .models import SimpleModel
+
+
+class DatabaseConnectionTest(SimpleTestCase):
+    """A database connection cannot be used in an async context."""
+    @async_to_sync
+    async def test_get_async_connection(self):
+        with self.assertRaises(SynchronousOnlyOperation):
+            list(SimpleModel.objects.all())
+
+
+class AsyncUnsafeTest(SimpleTestCase):
+    """
+    async_unsafe decorator should work correctly and returns the correct
+    message.
+    """
+    @async_unsafe
+    def dangerous_method(self):
+        return True
+
+    @async_to_sync
+    async def test_async_unsafe(self):
+        # async_unsafe decorator catches bad access and returns the right
+        # message.
+        msg = (
+            'You cannot call this from an async context - use a thread or '
+            'sync_to_async.'
+        )
+        with self.assertRaisesMessage(SynchronousOnlyOperation, msg):
+            self.dangerous_method()
diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
index 8bb284e0c3..300af388e6 100644
--- a/tests/i18n/tests.py
+++ b/tests/i18n/tests.py
@@ -8,10 +8,9 @@ import tempfile
 from contextlib import contextmanager
 from importlib import import_module
 from pathlib import Path
-from threading import local
 from unittest import mock
 
-import _thread
+from asgiref.local import Local
 
 from django import forms
 from django.apps import AppConfig
@@ -289,7 +288,7 @@ class TranslationTests(SimpleTestCase):
 
     @override_settings(LOCALE_PATHS=extended_locale_paths)
     def test_pgettext(self):
-        trans_real._active = local()
+        trans_real._active = Local()
         trans_real._translations = {}
         with translation.override('de'):
             self.assertEqual(pgettext("unexisting", "May"), "May")
@@ -310,7 +309,7 @@ class TranslationTests(SimpleTestCase):
         Translating a string requiring no auto-escaping with gettext or pgettext
         shouldn't change the "safe" status.
         """
-        trans_real._active = local()
+        trans_real._active = Local()
         trans_real._translations = {}
         s1 = mark_safe('Password')
         s2 = mark_safe('May')
@@ -1882,7 +1881,7 @@ class TranslationFileChangedTests(SimpleTestCase):
         self.assertEqual(gettext_module._translations, {})
         self.assertEqual(trans_real._translations, {})
         self.assertIsNone(trans_real._default)
-        self.assertIsInstance(trans_real._active, _thread._local)
+        self.assertIsInstance(trans_real._active, Local)
 
 
 class UtilsTests(SimpleTestCase):
diff --git a/tests/template_tests/syntax_tests/i18n/test_blocktrans.py b/tests/template_tests/syntax_tests/i18n/test_blocktrans.py
index ac8fc16da8..744b410ea6 100644
--- a/tests/template_tests/syntax_tests/i18n/test_blocktrans.py
+++ b/tests/template_tests/syntax_tests/i18n/test_blocktrans.py
@@ -1,5 +1,6 @@
 import os
-from threading import local
+
+from asgiref.local import Local
 
 from django.template import Context, Template, TemplateSyntaxError
 from django.test import SimpleTestCase, override_settings
@@ -278,7 +279,7 @@ class TranslationBlockTransTagTests(SimpleTestCase):
     @override_settings(LOCALE_PATHS=extended_locale_paths)
     def test_template_tags_pgettext(self):
         """{% blocktrans %} takes message contexts into account (#14806)."""
-        trans_real._active = local()
+        trans_real._active = Local()
         trans_real._translations = {}
         with translation.override('de'):
             # Nonexistent context
diff --git a/tests/template_tests/syntax_tests/i18n/test_trans.py b/tests/template_tests/syntax_tests/i18n/test_trans.py
index ba5021a5d5..47a79ff74d 100644
--- a/tests/template_tests/syntax_tests/i18n/test_trans.py
+++ b/tests/template_tests/syntax_tests/i18n/test_trans.py
@@ -1,4 +1,4 @@
-from threading import local
+from asgiref.local import Local
 
 from django.template import Context, Template, TemplateSyntaxError
 from django.templatetags.l10n import LocalizeNode
@@ -136,7 +136,7 @@ class TranslationTransTagTests(SimpleTestCase):
     @override_settings(LOCALE_PATHS=extended_locale_paths)
     def test_template_tags_pgettext(self):
         """{% trans %} takes message contexts into account (#14806)."""
-        trans_real._active = local()
+        trans_real._active = Local()
         trans_real._translations = {}
         with translation.override('de'):
             # Nonexistent context...