feat(service): validate explicit in_signature arity against method parameters

Author: bluetoothbot

src/dbus_fast/service.py

@@ -78,9 +78,15 @@ def __init__(
                 for i, param in enumerate(inspection.parameters.values())
                 if i != 0
             ]
-            for i, type_ in enumerate(get_signature_tree(in_signature).types):
-                arg_name = param_names[i] if i < len(param_names) else None
-                in_args.append(intr.Arg(type_, intr.ArgDirection.IN, arg_name))
+            types = get_signature_tree(in_signature).types
+            if len(types) != len(param_names):
+                raise ValueError(
+                    "in_signature has "
+                    f"{len(types)} complete type(s) but the method takes "
+                    f"{len(param_names)} parameter(s)"
+                )
+            for i, type_ in enumerate(types):
+                in_args.append(intr.Arg(type_, intr.ArgDirection.IN, param_names[i]))
 
         out_args: list[intr.Arg] = []
         if out_signature is None:

tests/service/test_decorator_signatures.py

@@ -1,3 +1,5 @@
+import asyncio
+
 import pytest
 
 from dbus_fast import Message, MessageType, PropertyAccess
@@ -176,3 +178,5 @@ async def test_decorator_signature_round_trip():
 
     bus1.disconnect()
     bus2.disconnect()
+    await asyncio.wait_for(bus1.wait_for_disconnect(), timeout=1)
+    await asyncio.wait_for(bus2.wait_for_disconnect(), timeout=1)