Fixed #16678 -- Wrote tests for contrib.redirects app

Thanks Julien Phalip for the report.

django/contrib/redirects/tests.py

+from django.conf import settings
+from django.contrib.sites.models import Site
+from django.test import TestCase
+from django.test.utils import override_settings
+from django.utils import six
+
+from .models import Redirect
+
+
+@override_settings(
+    SITE_ID=1,
+    APPEND_SLASH=True,
+    MIDDLEWARE_CLASSES=list(settings.MIDDLEWARE_CLASSES) +
+        ['django.contrib.redirects.middleware.RedirectFallbackMiddleware'],
+)
+class RedirectTests(TestCase):
+
+    def setUp(self):
+        self.site = Site.objects.get(pk=settings.SITE_ID)
+
+    def test_model(self):
+        r1 = Redirect.objects.create(
+            site=self.site, old_path='/initial', new_path='/new_target')
+        self.assertEqual(six.text_type(r1), "/initial ---> /new_target")
+
+    def test_redirect_middleware(self):
+        r1 = Redirect.objects.create(
+            site=self.site, old_path='/initial', new_path='/new_target')
+        response = self.client.get('/initial')
+        self.assertRedirects(response,
+            '/new_target', status_code=301, target_status_code=404)
+        # Works also with trailing slash
+        response = self.client.get('/initial/')
+        self.assertRedirects(response,
+            '/new_target', status_code=301, target_status_code=404)
+
+    def test_response_gone(self):
+        """When the redirect target is '', return a 410"""
+        r1 = Redirect.objects.create(
+            site=self.site, old_path='/initial', new_path='')
+        response = self.client.get('/initial')
+        self.assertEqual(response.status_code, 410)