treat retrieval of an incompatible message from history as a "message…

golem/network/history.py

@@ -119,7 +119,13 @@ def get_sync_as_message(cls, *args, **kwargs) -> message.base.Message:
         if not db_result:
             raise MessageNotFound()
         db_msg = db_result[0]
-        return db_msg.as_message()
+        try:
+            return db_msg.as_message()
+        except AttributeError:
+            # in case an incompatible message from an earlier version of
+            # golem-messages is retrieved, just treat it the same
+            # as if the message was not found
+            raise MessageNotFound()
 
     def add(self, msg_dict: dict) -> None:
         """

tests/golem/network/test_history.py

@@ -21,8 +21,7 @@
 def message_count():
     return NetworkMessage.select().count()
 
-
-class TestMessageHistoryService(DatabaseFixture):
+class MessageHistoryServiceTestBase(DatabaseFixture):
 
     def setUp(self):
         super().setUp()
@@ -32,6 +31,8 @@ def tearDown(self):
         super().tearDown()
         history.MessageHistoryService.instance = None
 
+
+class TestMessageHistoryService(MessageHistoryServiceTestBase):
     @staticmethod
     def _build_dict(task=None, subtask=None):
         return dict(
@@ -256,6 +257,46 @@ def test_loop_remove_sync(self):
         assert not self.service.remove_sync.called
 
 
+class TestMessageHistoryGet(MessageHistoryServiceTestBase):
+    def setUp(self):
+        super().setUp()
+        self.msg = msg_factories.tasks.TaskToComputeFactory()
+        self.msg._fake_sign()
+        self.node_id = fake.binary(length=64)
+        self.local_role = fake.random_element(Actor)
+        self.remote_role = fake.random_element(Actor)
+
+        history.add(
+            msg=self.msg,
+            node_id=self.node_id,
+            local_role=self.local_role,
+            remote_role=self.remote_role,
+            sync=True
+        )
+
+    def test_get(self):
+        msg_retrieved = history.get(
+            'TaskToCompute',
+            subtask_id=self.msg.subtask_id,
+            node_id=self.node_id,
+        )
+
+        self.assertEqual(self.msg, msg_retrieved)
+
+    def test_get_pickle_fail(self):
+        with mock.patch(
+                'golem.model.pickle.loads',
+                mock.Mock(side_effect=AttributeError)
+        ):
+            msg_retrieved = history.get(
+                'TaskToCompute',
+                subtask_id=self.msg.subtask_id,
+                node_id=self.node_id,
+            )
+
+        self.assertIsNone(msg_retrieved)
+
+
 @mock.patch("golem.network.history.MessageHistoryService.add")
 class TestAdd(unittest.TestCase):
     def setUp(self):