Skip interceptor for methods that are not registered in the server

src/grpc_interceptor/server.py

@@ -121,6 +121,10 @@ async def intercept_service(self, continuation, handler_call_details):
         have a public name. Do not override it, unless you know what you're doing.
         """
         next_handler = await continuation(handler_call_details)
+        # Returns None if the method isn't implemented.
+        if not next_handler:
+            return
+
         handler_factory, next_handler_method = _get_factory_and_method(next_handler)
 
         if next_handler.response_streaming:

tests/test_server.py

@@ -177,15 +177,19 @@ def test_aborting_interceptor(aio):
         assert e.value.details() == "oh no"
 
 
-def test_method_not_found():
+@pytest.mark.parametrize("aio", [False, True])
+def test_method_not_found(aio):
     """Calling undefined endpoints should return Unimplemented.
 
     Interceptors are not invoked when the RPC call is not handled.
     """
-    intr = CountingInterceptor()
+    intr_type = AsyncCountingInterceptor if aio else CountingInterceptor
+    intr = intr_type()
     interceptors = [intr]
 
-    with dummy_channel(special_cases={}, interceptors=interceptors) as channel:
+    with dummy_channel(
+        special_cases={}, interceptors=interceptors, aio_server=aio
+    ) as channel:
         with pytest.raises(grpc.RpcError) as e:
             channel.unary_unary(
                 "/DummyService/Unimplemented",