Fix #863: Request Support for $min, $max Field update operators

tests/queryset/queryset.py

@@ -510,6 +510,17 @@ class QuerySetTest(unittest.TestCase):
         self.assertEqual(post.comments[0].by, 'joe')
         self.assertEqual(post.comments[0].votes.score, 4)
 
+    def test_update_min_max(self):
+        class Scores(Document):
+            high_score = IntField()
+            low_score = IntField()
+        scores = Scores(high_score=800, low_score=200)
+        scores.save()
+        Scores.objects(id=scores.id).update(min__low_score=150)
+        self.assertEqual(Scores.objects(id=scores.id).get().low_score, 150)
+        Scores.objects(id=scores.id).update(min__low_score=250)
+        self.assertEqual(Scores.objects(id=scores.id).get().low_score, 150)
+
     def test_updates_can_have_match_operators(self):
 
         class Comment(EmbeddedDocument):