Merge ~cgrabowski/maas:fix_unsubscribe_response_serialization into maas:master

[Christian Grabowski]

ensure type returned on unsubscribe is always list

[Jack Lloyd-Walters (lloydwaltersj)]

review: Approve

[Adam Collard (adam-collard)]

review: Needs Information

[MAAS Lander (maas-lander)]

UNIT TESTS
-b fix_unsubscribe_response_serialization lp:~cgrabowski/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci.internal:8080/job/maas-tester/118/consoleText
COMMIT: 36974c574d417b3d9e65a2c2de9020237f66e798

review: Needs Fixing

[MAAS Lander (maas-lander)]

UNIT TESTS
-b fix_unsubscribe_response_serialization lp:~cgrabowski/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: f6a1cc5ce7089ff302bf8798038869f7e656fd4e

review: Approve

[MAAS Lander (maas-lander)]

LANDING
-b fix_unsubscribe_response_serialization lp:~cgrabowski/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: FAILED BUILD
LOG: http://maas-ci.internal:8080/job/maas-tester/121/consoleText

diff --git a/src/maasserver/websockets/base.py b/src/maasserver/websockets/base.py
index 8787174..a9cd089 100644
--- a/src/maasserver/websockets/base.py
+++ b/src/maasserver/websockets/base.py
@@ -831,7 +831,7 @@ class Handler(metaclass=HandlerMetaclass):
             if self.cache.get("active_pk") in pks:
                 del self.cache["active_pk"]
             self.cache["loaded_pks"] = self.cache["loaded_pks"] - pks
-            return pks
+            return list(pks)
         else:
             raise HandlerValidationError(
                 f"'{self._meta.pk}' or '{self._meta.bulk_pk}' must be provided in params for unsubscribe"
diff --git a/src/maasserver/websockets/handlers/tests/test_machine.py b/src/maasserver/websockets/handlers/tests/test_machine.py
index 369ae81..9ffcbcd 100644
--- a/src/maasserver/websockets/handlers/tests/test_machine.py
+++ b/src/maasserver/websockets/handlers/tests/test_machine.py
@@ -6291,6 +6291,16 @@ class TestMachineHandlerFilter(MAASServerTestCase):
         handler = MachineHandler(admin, {}, None)
         self.assertRaises(HandlerValidationError, handler.unsubscribe, {})
 
+    def test_unsubscribe_returns_serializable_type(self):
+        admin = factory.make_admin()
+        handler = MachineHandler(admin, {}, None)
+        nodes = [factory.make_Node() for _ in range(3)]
+        handler.list({})
+        resp = handler.unsubscribe(
+            {"system_ids": [node.system_id for node in nodes]}
+        )
+        self.assertIsInstance(resp, list)
+
     def test_read_an_unsubscribed_object_subscribes(self):
         admin = factory.make_admin()
         handler = MachineHandler(admin, {}, None)