Adding test case for self-referencing documents with cascade deletes

tests/queryset.py

@@ -1344,6 +1344,37 @@ class QuerySetTest(unittest.TestCase):
         self.Person.objects(name='Test User').delete()
         self.assertEqual(1, BlogPost.objects.count())
 
+    def test_reverse_delete_rule_cascade_self_referencing(self):
+        """Ensure self-referencing CASCADE deletes do not result in infinite loop
+        """
+        class Category(Document):
+            name = StringField()
+            parent = ReferenceField('self', reverse_delete_rule=CASCADE)
+
+        num_children = 3
+        base = Category(name='Root')
+        base.save()
+
+        # Create a simple parent-child tree
+        for i in range(num_children):
+            child_name = 'Child-%i' % i
+            child = Category(name=child_name, parent=base)
+            child.save()
+
+            for i in range(num_children):
+                child_child_name = 'Child-Child-%i' % i
+                child_child = Category(name=child_child_name, parent=child)
+                child_child.save()
+
+        tree_size = 1 + num_children + (num_children * num_children)
+        self.assertEquals(tree_size, Category.objects.count())
+        self.assertEquals(num_children, Category.objects(parent=base).count())
+
+        # The delete should effectively wipe out the Category collection
+        # without resulting in infinite parent-child cascade recursion
+        base.delete()
+        self.assertEquals(0, Category.objects.count())
+
     def test_reverse_delete_rule_nullify(self):
         """Ensure nullification of references to deleted documents.
         """