Enhance the value error when missing a reqiured param.

fed/_private/fed_call_holder.py

@@ -56,6 +56,9 @@ def options(self, **options):
         return self
 
     def internal_remote(self, *args, **kwargs):
+        if not self._node_party:
+            raise ValueError("You should specify a party name on the fed actor.")
+
         # Generate a new fed task id for this call.
         fed_task_id = get_global_context().next_seq_id()
         if self._party == self._node_party:

fed/api.py

@@ -300,9 +300,9 @@ def options(self, **options):
         return self
 
     def remote(self, *args, **kwargs):
-        assert (
-            self._node_party is not None
-        ), "A fed function should be specified within a party to execute."
+        if not self._node_party:
+            raise ValueError("You should specify a party name on the fed function.")
+
         return self._fed_call_holder.internal_remote(*args, **kwargs)
 
     def _execute_impl(self, args, kwargs):

tests/test_api.py

@@ -40,6 +40,30 @@ def test_fed_apis():
     assert p_alice.exitcode == 0
 
 
+def test_miss_party_name_on_actor():
+    def run():
+        compatible_utils.init_ray(address='local')
+        cluster = {
+            'alice': {'address': '127.0.0.1:11012'},
+        }
+        fed.init(cluster=cluster, party="alice")
+
+        @fed.remote
+        class MyActor:
+            pass
+
+        with pytest.raises(ValueError):
+            MyActor.remote()
+
+        fed.shutdown()
+        ray.shutdown()
+
+    p_alice = multiprocessing.Process(target=run)
+    p_alice.start()
+    p_alice.join()
+    assert p_alice.exitcode == 0
+
+
 if __name__ == "__main__":
     import sys