Add a limit to the update_policy_state_for_assignment loop to prevent

infinite loops, e.g. when a team has only a single reviewer.
 - Legacy-Id: 17087

Author: Sasha Romijn

ietf/review/policies.py

@@ -92,10 +92,13 @@ def reviewer_at_index(i):
 
         # Loop through the list until finding the first person with skip_next=0,
         # who is not the current assignee. Anyone with skip_next>0 encountered before
-        # has their skip_next decreased.
+        # has their skip_next decreased. There is a cap on the number of loops, which can
+        # be hit e.g. if there is only a single reviewer, and the current assignee is excluded
+        # from being set as NextReviewerInTeam.
         current_idx = 0
+        max_loops = sum([self._reviewer_settings_for(r).skip_next for r in rotation_list]) + len(rotation_list)
         if in_order_assignment:
-            while True:
+            while current_idx <= max_loops:
                 current_idx_person = reviewer_at_index(current_idx)
                 settings = self._reviewer_settings_for(current_idx_person)
                 if settings.skip_next > 0:

ietf/review/test_policies.py

@@ -198,6 +198,15 @@ def get_skip_next(person):
         self.assertEqual(get_skip_next(reviewers[3]), 1)
         self.assertEqual(get_skip_next(reviewers[4]), 0)
 
+        # Leave only a single reviewer remaining, which should not trigger an infinite loop.
+        # The deletion also causes NextReviewerInTeam to be deleted.
+        [reviewer.delete() for reviewer in reviewers[1:]]
+        self.assertEqual([reviewers[0]], policy.default_reviewer_rotation_list())
+        policy.update_policy_state_for_assignment(assignee_person=reviewers[0], add_skip=False)
+        # No NextReviewerInTeam should be created, the only possible next is the excluded assignee.
+        self.assertFalse(NextReviewerInTeam.objects.filter(team=team))
+        self.assertEqual([reviewers[0]], policy.default_reviewer_rotation_list())
+
     def test_return_reviewer_to_top_rotation(self):
         team = ReviewTeamFactory(acronym="rotationteam", name="Review Team",
                                  list_email="rotationteam@ietf.org",