Fixed #32260 -- Made View.as_view() do not use update_wrapper().

View.as_view() should not use update_wrapper() for copying attributes
it's unintended and have side-effects such as adding `self` to the
signature.

This also fixes system check for arguments of custom error handler
views with class-based views.

Co-authored-by: Nick Pope <nick.pope@flightdataservices.com>

5 files changed, 61 insertions, 6 deletions

diff --git a/tests/check_framework/test_urls.py b/tests/check_framework/test_urls.py
index f0c257bc77..2ef3d5b07f 100644
--- a/tests/check_framework/test_urls.py
+++ b/tests/check_framework/test_urls.py
@@ -167,20 +167,41 @@ class UpdatedToPathTests(SimpleTestCase):
 
 class CheckCustomErrorHandlersTests(SimpleTestCase):
 
-    @override_settings(ROOT_URLCONF='check_framework.urls.bad_error_handlers')
-    def test_bad_handlers(self):
+    @override_settings(
+        ROOT_URLCONF='check_framework.urls.bad_function_based_error_handlers',
+    )
+    def test_bad_function_based_handlers(self):
         result = check_url_config(None)
         self.assertEqual(len(result), 4)
         for code, num_params, error in zip([400, 403, 404, 500], [2, 2, 2, 1], result):
             with self.subTest('handler{}'.format(code)):
                 self.assertEqual(error, Error(
-                    "The custom handler{} view "
-                    "'check_framework.urls.bad_error_handlers.bad_handler' "
+                    "The custom handler{} view 'check_framework.urls."
+                    "bad_function_based_error_handlers.bad_handler' "
                     "does not take the correct number of arguments (request{})."
                     .format(code, ', exception' if num_params == 2 else ''),
                     id='urls.E007',
                 ))
 
+    @override_settings(
+        ROOT_URLCONF='check_framework.urls.bad_class_based_error_handlers',
+    )
+    def test_bad_class_based_handlers(self):
+        result = check_url_config(None)
+        self.assertEqual(len(result), 4)
+        for code, num_params, error in zip([400, 403, 404, 500], [2, 2, 2, 1], result):
+            with self.subTest('handler%s' % code):
+                self.assertEqual(error, Error(
+                    "The custom handler%s view 'check_framework.urls."
+                    "bad_class_based_error_handlers.HandlerView.as_view."
+                    "<locals>.view' does not take the correct number of "
+                    "arguments (request%s)." % (
+                        code,
+                        ', exception' if num_params == 2 else '',
+                    ),
+                    id='urls.E007',
+                ))
+
     @override_settings(ROOT_URLCONF='check_framework.urls.bad_error_handlers_invalid_path')
     def test_bad_handlers_invalid_path(self):
         result = check_url_config(None)
@@ -204,8 +225,17 @@ class CheckCustomErrorHandlersTests(SimpleTestCase):
                     id='urls.E008',
                 ))
 
-    @override_settings(ROOT_URLCONF='check_framework.urls.good_error_handlers')
-    def test_good_handlers(self):
+    @override_settings(
+        ROOT_URLCONF='check_framework.urls.good_function_based_error_handlers',
+    )
+    def test_good_function_based_handlers(self):
+        result = check_url_config(None)
+        self.assertEqual(result, [])
+
+    @override_settings(
+        ROOT_URLCONF='check_framework.urls.good_class_based_error_handlers',
+    )
+    def test_good_class_based_handlers(self):
         result = check_url_config(None)
         self.assertEqual(result, [])
 
diff --git a/tests/check_framework/urls/bad_class_based_error_handlers.py b/tests/check_framework/urls/bad_class_based_error_handlers.py
new file mode 100644
index 0000000000..346e7f59be
--- /dev/null
+++ b/tests/check_framework/urls/bad_class_based_error_handlers.py
@@ -0,0 +1,16 @@
+urlpatterns = []
+
+
+class HandlerView:
+    @classmethod
+    def as_view(cls):
+        def view():
+            pass
+
+        return view
+
+
+handler400 = HandlerView.as_view()
+handler403 = HandlerView.as_view()
+handler404 = HandlerView.as_view()
+handler500 = HandlerView.as_view()
diff --git a/tests/check_framework/urls/bad_error_handlers.py b/tests/check_framework/urls/bad_function_based_error_handlers.py
index d639d707df..d639d707df 100644
--- a/tests/check_framework/urls/bad_error_handlers.py
+++ b/tests/check_framework/urls/bad_function_based_error_handlers.py
diff --git a/tests/check_framework/urls/good_class_based_error_handlers.py b/tests/check_framework/urls/good_class_based_error_handlers.py
new file mode 100644
index 0000000000..56e6408a71
--- /dev/null
+++ b/tests/check_framework/urls/good_class_based_error_handlers.py
@@ -0,0 +1,9 @@
+from django.views.generic import View
+
+urlpatterns = []
+
+
+handler400 = View.as_view()
+handler403 = View.as_view()
+handler404 = View.as_view()
+handler500 = View.as_view()
diff --git a/tests/check_framework/urls/good_error_handlers.py b/tests/check_framework/urls/good_function_based_error_handlers.py
index 69bea650f7..69bea650f7 100644
--- a/tests/check_framework/urls/good_error_handlers.py
+++ b/tests/check_framework/urls/good_function_based_error_handlers.py