issue #23 - unit test coverage

amqp/adapter/type_descriptor.py

@@ -107,10 +107,7 @@ def _instantiate(
         TypeError: If instantiation fails
     """
     # Handle JSON payload first
-    try:
-        json_payload = json.loads(payload) if is_json and isinstance(payload, str) else None
-    except Exception:
-        json_payload = None
+    json_payload = json.loads(payload) if is_json and isinstance(payload, str) else None
 
     # Handle basic types
     if type_string == "str":
@@ -143,12 +140,22 @@ def _instantiate(
         if type_string.startswith("typing.Set"):
             if json_payload is not None:
                 return set(json_payload)
-            return set(payload if isinstance(payload, list) else payload.split(","))
+            _set_type = _extract_type_of(type_string)
+            return set(
+                payload
+                if isinstance(payload, list)
+                else [_instantiate(_set_type, p) for p in payload.split(",")]
+            )
 
         if type_string.startswith("typing.Tuple"):
             if json_payload is not None:
                 return tuple(json_payload)
-            return tuple(payload if isinstance(payload, list) else payload.split(","))
+            _tuple_type = _extract_type_of(type_string)
+            return tuple(
+                payload
+                if isinstance(payload, list)
+                else [_instantiate(_tuple_type, p) for p in payload.split(",")]
+            )
 
         if type_string.startswith("typing.Optional"):
             inner_type = _extract_type_of(type_string)