minor fixes to pass mypy and cov

Author: rmorshea

idom/core/layout.py

@@ -4,6 +4,7 @@
     List,
     Dict,
     Tuple,
+    Mapping,
     NamedTuple,
     Any,
     Set,
@@ -145,16 +146,17 @@ async def _render_element(self, element_state: ElementState) -> Dict[str, Any]:
         return element_state.model
 
     async def _render_model(
-        self, element_state: ElementState, model: Dict[str, Any]
+        self, element_state: ElementState, model: Mapping[str, Any]
     ) -> Dict[str, Any]:
+        serialized_model: Dict[str, Any] = {}
         event_handlers = self._render_model_event_targets(element_state, model)
         if event_handlers:
-            model["eventHandlers"] = event_handlers
+            serialized_model["eventHandlers"] = event_handlers
         if "children" in model:
-            model["children"] = await self._render_model_children(
+            serialized_model["children"] = await self._render_model_children(
                 element_state, model["children"]
             )
-        return model
+        return {**model, **serialized_model}
 
     async def _render_model_children(
         self, element_state: ElementState, children: Union[List[Any], Tuple[Any, ...]]
@@ -176,7 +178,7 @@ async def _render_model_children(
         return resolved_children
 
     def _render_model_event_targets(
-        self, element_state: ElementState, model: Dict[str, Any]
+        self, element_state: ElementState, model: Mapping[str, Any]
     ) -> Dict[str, EventTarget]:
         handlers: Dict[str, EventHandler] = {}
         if "eventHandlers" in model:

tests/test_core/test_hooks.py

@@ -546,7 +546,11 @@ async def test_use_callback_memoization():
     @element_hook.capture
     async def ElementWithRef():
         state, set_state_hook.current = idom.hooks.use_state(0)
-        cb = idom.hooks.use_callback(lambda: None, [state])
+
+        @idom.hooks.use_callback(args=[state])  # use the deco form for coverage
+        def cb():
+            return None
+
         used_callbacks.append(cb)
         return idom.html.div()