Refs #31949 -- Made @vary_on_(cookie/headers) decorators work with async functions.

tests/decorators/test_vary.py

@@ -0,0 +1,69 @@
+from asgiref.sync import iscoroutinefunction
+
+from django.http import HttpRequest, HttpResponse
+from django.test import SimpleTestCase
+from django.views.decorators.vary import vary_on_cookie, vary_on_headers
+
+
+class VaryOnHeadersTests(SimpleTestCase):
+    def test_wrapped_sync_function_is_not_coroutine_function(self):
+        def sync_view(request):
+            return HttpResponse()
+
+        wrapped_view = vary_on_headers()(sync_view)
+        self.assertIs(iscoroutinefunction(wrapped_view), False)
+
+    def test_wrapped_async_function_is_coroutine_function(self):
+        async def async_view(request):
+            return HttpResponse()
+
+        wrapped_view = vary_on_headers()(async_view)
+        self.assertIs(iscoroutinefunction(wrapped_view), True)
+
+    def test_vary_on_headers_decorator(self):
+        @vary_on_headers("Header", "Another-header")
+        def sync_view(request):
+            return HttpResponse()
+
+        response = sync_view(HttpRequest())
+        self.assertEqual(response.get("Vary"), "Header, Another-header")
+
+    async def test_vary_on_headers_decorator_async_view(self):
+        @vary_on_headers("Header", "Another-header")
+        async def async_view(request):
+            return HttpResponse()
+
+        response = await async_view(HttpRequest())
+        self.assertEqual(response.get("Vary"), "Header, Another-header")
+
+
+class VaryOnCookieTests(SimpleTestCase):
+    def test_wrapped_sync_function_is_not_coroutine_function(self):
+        def sync_view(request):
+            return HttpResponse()
+
+        wrapped_view = vary_on_cookie(sync_view)
+        self.assertIs(iscoroutinefunction(wrapped_view), False)
+
+    def test_wrapped_async_function_is_coroutine_function(self):
+        async def async_view(request):
+            return HttpResponse()
+
+        wrapped_view = vary_on_cookie(async_view)
+        self.assertIs(iscoroutinefunction(wrapped_view), True)
+
+    def test_vary_on_cookie_decorator(self):
+        @vary_on_cookie
+        def sync_view(request):
+            return HttpResponse()
+
+        response = sync_view(HttpRequest())
+        self.assertEqual(response.get("Vary"), "Cookie")
+
+    async def test_vary_on_cookie_decorator_async_view(self):
+        @vary_on_cookie
+        async def async_view(request):
+            return HttpResponse()
+
+        response = await async_view(HttpRequest())
+        self.assertEqual(response.get("Vary"), "Cookie")