Test periodic grouping returns most recent first

backdrop/core/database.py

@@ -85,7 +85,7 @@ def multi_group(self, key1, key2, query):
         output = nested_merge([key1, key2], results)
 
         result = []
-        for key1_value, value in sorted(output.items()):
+        for key1_value, value in sorted(output.items(), reverse=True):
             result.append({
                 key1: key1_value,
                 "_count": sum(doc['_count'] for doc in value.values()),

tests/core/integration/test_database_integration.py

@@ -389,7 +389,6 @@ def test_sorted_query_with_alphanumeric(self):
             has_entry('val', 'a')
         ))
 
-
     def test_sorted_group_ascending(self):
         self.mongo_collection.save({"suite": "clubs"})
         self.mongo_collection.save({"suite": "hearts"})
@@ -463,3 +462,16 @@ def test_sorted_group_by_count(self):
             has_entry("suite", "hearts"),
             has_entry("suite", "clubs")
         ))
+
+    def test_periodic_group_is_sorted_by__week_start_at(self):
+        self.mongo_collection.save({"_week_start_at": d(2013, 3, 17),
+                                    'val': 1})
+        self.mongo_collection.save({"_week_start_at": d(2013, 3, 24),
+                                    'val': 7})
+
+        result = self.repo.multi_group('_week_start_at', 'val', {})
+
+        assert_that(list(result), contains(
+            has_entry('_week_start_at', d(2013, 3, 24)),
+            has_entry('_week_start_at', d(2013, 3, 17))
+        ))