feat(poll): make exact transitions idempotent

tests/test_lifecycle.py

@@ -266,12 +266,86 @@ class PollLifecycleTests(unittest.TestCase):
                 idempotency_key="decision-2",
             )
 
-    def test_repeated_exact_transition_without_an_identity_is_rejected(self) -> None:
+    def test_repeated_exact_transition_without_an_identity_is_an_audit_free_noop(self) -> None:
+        poll = self._poll()
+        applied = transition_poll(self.session, tenant_id="tenant-1", poll_id=poll.id, action="open")
+
+        with self.assertLogs("govoplan.poll.lifecycle", level="INFO") as logs:
+            repeated = transition_poll(
+                self.session,
+                tenant_id="tenant-1",
+                poll_id=poll.id,
+                action="open",
+                actor_user_id="owner",
+            )
+
+        self.assertFalse(applied.replayed)
+        self.assertTrue(repeated.replayed)
+        self.assertIsNone(repeated.transition)
+        self.assertEqual(poll.status, "open")
+        self.assertEqual(len(poll.lifecycle_transitions), 1)
+        self.assertIn("Ignored repeated exact Poll lifecycle transition", logs.output[0])
+
+    def test_same_decision_is_a_noop_but_a_changed_decision_is_audited(self) -> None:
         poll = self._poll()
         transition_poll(self.session, tenant_id="tenant-1", poll_id=poll.id, action="open")
+        transition_poll(self.session, tenant_id="tenant-1", poll_id=poll.id, action="close")
+        first = transition_poll(
+            self.session,
+            tenant_id="tenant-1",
+            poll_id=poll.id,
+            action="decide",
+            option_key="yes",
+        )
+        repeated = transition_poll(
+            self.session,
+            tenant_id="tenant-1",
+            poll_id=poll.id,
+            action="decide",
+            option_key="yes",
+        )
+        changed = transition_poll(
+            self.session,
+            tenant_id="tenant-1",
+            poll_id=poll.id,
+            action="decide",
+            option_key="no",
+        )
 
+        self.assertTrue(repeated.replayed)
+        self.assertIsNone(repeated.transition)
+        self.assertIsNotNone(first.transition)
+        self.assertIsNotNone(changed.transition)
+        self.assertEqual(changed.transition.previous_decision_option_id, first.transition.decision_option_id)
+        self.assertEqual(
+            [item.action for item in poll.lifecycle_transitions],
+            ["open", "close", "decide", "decide"],
+        )
+
+    def test_exact_unarchive_retry_is_a_noop_but_unarchive_without_history_is_invalid(self) -> None:
+        poll = self._poll()
+        transition_poll(self.session, tenant_id="tenant-1", poll_id=poll.id, action="archive")
+        transition_poll(self.session, tenant_id="tenant-1", poll_id=poll.id, action="unarchive")
+
+        repeated = transition_poll(
+            self.session,
+            tenant_id="tenant-1",
+            poll_id=poll.id,
+            action="unarchive",
+        )
+
+        self.assertTrue(repeated.replayed)
+        self.assertIsNone(repeated.transition)
+        self.assertEqual([item.action for item in poll.lifecycle_transitions], ["archive", "unarchive"])
+
+        never_archived = self._poll(title="Never archived")
         with self.assertRaisesRegex(PollError, "not allowed"):
-            transition_poll(self.session, tenant_id="tenant-1", poll_id=poll.id, action="open")
+            transition_poll(
+                self.session,
+                tenant_id="tenant-1",
+                poll_id=never_archived.id,
+                action="unarchive",
+            )
 
     def test_archive_and_unarchive_restore_status_and_append_audit_history(self) -> None:
         poll = self._poll()
@@ -444,6 +518,7 @@ class PollLifecycleTests(unittest.TestCase):
         self.assertEqual(opened.poll.status, "open")
         self.assertFalse(opened.replayed)
         self.assertTrue(replay.replayed)
+        self.assertIsNotNone(replay.transition)
         self.assertEqual(len(lifecycle.history), 1)
         self.assertEqual(lifecycle.history[0].actor_user_id, "owner-membership")
         self.assertEqual(
@@ -462,6 +537,27 @@ class PollLifecycleTests(unittest.TestCase):
             )
         self.assertEqual(rejected.exception.status_code, 400)
 
+    def test_generic_api_returns_null_transition_for_domain_noop(self) -> None:
+        poll = self._poll(status="open", title="Already open")
+
+        repeated = api_transition_poll(
+            poll.id,
+            PollTransitionRequest(action="open"),
+            idempotency_key=None,
+            session=self.session,
+            principal=self._principal(),
+        )
+
+        self.assertEqual(repeated.poll.status, "open")
+        self.assertTrue(repeated.replayed)
+        self.assertIsNone(repeated.transition)
+        self.assertEqual(
+            self.session.query(PollLifecycleTransition)
+            .filter(PollLifecycleTransition.poll_id == poll.id)
+            .count(),
+            0,
+        )
+
 
 if __name__ == "__main__":
     unittest.main()