Fix the caching of featured projects (#7054)

* Fix the caching of featured projects

Currently the `if` block actually evaluates the queryset,
causing it never to actually cache the query that we want it to cache.

* Add homepage cache tests

* Don’t test logged in queries because they vary too much.

* Clear cache on both sides

Author: ericholscher

readthedocs/rtd_tests/tests/test_views.py

@@ -7,6 +7,7 @@
 from django.urls import reverse
 from django.utils import timezone
 from django_dynamic_fixture import get, new
+from django.core.cache import cache
 
 from readthedocs.builds.constants import EXTERNAL, LATEST
 from readthedocs.builds.models import Build, Version
@@ -359,3 +360,22 @@ def test_generated_csv_data(self):
             self.assertEqual(len(body), 23)
             self.assertEqual(body[0][1], 'advertising')
             self.assertEqual(body[-1][1], 'hello world')
+
+
+class TestHomepageCache(TestCase):
+
+    def setUp(self):
+        cache.clear()
+
+    def tearDown(self):
+        cache.clear()
+
+    def test_homepage_queries(self):
+        with self.assertNumQueries(1):
+            r = self.client.get('/')
+            self.assertEqual(r.status_code, 200)
+
+        # Cache
+        with self.assertNumQueries(0):
+            r = self.client.get('/')
+            self.assertEqual(r.status_code, 200)

readthedocs/templates/homepage.html

@@ -114,9 +114,9 @@ <h3>Multiple versions</h3>
     {% include "core/widesearchbar.html" %}
   </section>
 
-  {% if featured_list %}
   {% get_current_language as language %}
   {% cache 600 homepage_featured_list language %}
+  {% if featured_list %}
     <!-- BEGIN projects list -->
     <section>
       <h3>{% trans "Featured Projects" %}</h3>
@@ -129,8 +129,8 @@ <h3>{% trans "Featured Projects" %}</h3>
       </div>
     </section>
     <!-- END projects list -->
-  {% endcache %}
   {% endif %}
+  {% endcache %}
 
   <!-- Funding and Contributing -->
   <section>