Derive DisciplineServer from the servicer base class (#70)

CHANGELOG.md

@@ -57,6 +57,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Bug Fixes
 
+- `DisciplineServer` inherited `DisciplineService`, the generated experimental
+  static-call API, rather than `DisciplineServiceServicer`, the servicer base
+  that `add_DisciplineServiceServicer_to_server` is written against.  No
+  shipping code path reached the difference, because `DisciplineServer`
+  overrides all eight RPCs itself, but the class did not inherit the
+  `UNIMPLEMENTED` defaults a servicer base provides.  An RPC left undefined --
+  for instance one added to the `.proto` and not yet implemented -- resolved
+  instead to a static client stub, which registers without complaint and then
+  fails at call time by treating the `ServicerContext` as a target address,
+  raising out of the handler without setting a status, so the caller saw
+  `UNKNOWN` rather than `UNIMPLEMENTED`.  The base is now
+  `DisciplineServiceServicer`, matching `ExplicitServer` and `ImplicitServer`
+  (#70).
+
 - Fixed `RemoteExplicitComponent` and `RemoteImplicitComponent` sending the raw
   constructor keyword arguments to the server rather than the component's
   resolved options.  An option that reached the component by any other route --

philote_mdo/general/discipline_server.py

@@ -46,7 +46,7 @@
 from philote_mdo.utils.validation import PhiloteValidationError, validate_shape
 
 
-class DisciplineServer(disc.DisciplineService):
+class DisciplineServer(disc.DisciplineServiceServicer):
     """
     Base class for all server classes.
     """

tests/test_discipline_server.py

@@ -38,6 +38,7 @@
 from philote_mdo.general import Discipline, DisciplineServer
 from philote_mdo.utils.validation import PhiloteValidationError
 import philote_mdo.generated.data_pb2 as data
+import philote_mdo.generated.disciplines_pb2_grpc as disc
 
 
 class TestDisciplineServer(unittest.TestCase):
@@ -610,6 +611,31 @@ def test_setup_general_exception_aborts(self):
         self.assertEqual(args[0][0], grpc.StatusCode.INTERNAL)
         self.assertIn("Setup failed", args[0][1])
 
+    def test_servicer_base_class(self):
+        """
+        Tests that the server derives from the servicer, not the static API.
+        """
+        self.assertTrue(issubclass(DisciplineServer, disc.DisciplineServiceServicer))
+        self.assertNotIn(disc.DisciplineService, DisciplineServer.__mro__)
+
+    def test_missing_rpc_falls_back_to_servicer_default(self):
+        """
+        Tests that an RPC a subclass fails to define resolves to the servicer's
+        UNIMPLEMENTED default rather than to the static-call API.
+        """
+        skip = ("__dict__", "__weakref__", "GetInfo")
+        attrs = {k: v for k, v in vars(DisciplineServer).items() if k not in skip}
+        partial_cls = type("PartialServer", DisciplineServer.__bases__, attrs)
+
+        # the inherited GetInfo must come from the servicer, not the static API
+        self.assertIs(partial_cls.GetInfo, disc.DisciplineServiceServicer.GetInfo)
+
+        context = Mock()
+        with self.assertRaises(NotImplementedError):
+            partial_cls().GetInfo(Empty(), context)
+
+        context.set_code.assert_called_once_with(grpc.StatusCode.UNIMPLEMENTED)
+
 
 if __name__ == "__main__":
     unittest.main(verbosity=2)