[1.8.x] Moved contrib.messages tests out of contrib.

Backport of b3cd9e0d07 from master

tests/messages_tests/test_middleware.py

@@ -0,0 +1,19 @@
+import unittest
+
+from django import http
+from django.contrib.messages.middleware import MessageMiddleware
+
+
+class MiddlewareTest(unittest.TestCase):
+
+    def setUp(self):
+        self.middleware = MessageMiddleware()
+
+    def test_response_without_messages(self):
+        """
+        Makes sure that the response middleware is tolerant of messages not
+        existing on request.
+        """
+        request = http.HttpRequest()
+        response = http.HttpResponse()
+        self.middleware.process_response(request, response)