Add worker delivery acceptance probe

tests/test_celery_queue_contract.py

@@ -1,8 +1,9 @@
 from __future__ import annotations
 
 import unittest
+from unittest.mock import patch
 
-from govoplan_core.celery_app import celery
+from govoplan_core.celery_app import celery, worker_acceptance_probe
 from govoplan_core.settings import settings
 
 
@@ -26,9 +27,33 @@ class CeleryQueueContractTests(unittest.TestCase):
     def test_delivery_tasks_keep_worker_loss_protection(self) -> None:
         self.assertTrue(celery.conf.task_acks_late)
         self.assertTrue(celery.conf.task_reject_on_worker_lost)
+        self.assertTrue(celery.conf.task_track_started)
         self.assertEqual(1, celery.conf.worker_prefetch_multiplier)
+        self.assertEqual(
+            settings.celery_visibility_timeout_seconds,
+            celery.conf.broker_transport_options["visibility_timeout"],
+        )
+
+    def test_worker_acceptance_probe_is_bounded_and_side_effect_free(self) -> None:
+        with patch.object(worker_acceptance_probe, "update_state") as update_state:
+            result = worker_acceptance_probe.run(
+                "probe-1",
+                mode="complete",
+                delay_seconds=0,
+            )
+
+        self.assertEqual(
+            {
+                "probe_id": "probe-1",
+                "mode": "complete",
+                "retries": 0,
+                "redelivered": False,
+                "delivery_count": None,
+            },
+            result,
+        )
+        update_state.assert_called_once()
 
 
 if __name__ == "__main__":
     unittest.main()
-