chore: address coverage issues

Clean up flow in of handling named tool call part.

Add no branch comments to the adapter and test files for cases which
only test one branch of the code and have no impact.

Author: stevenh

adapter_ag_ui/adapter_ag_ui/adapter.py

@@ -313,7 +313,7 @@ async def _tool_events(
                     pass
                 case Iterable() as iter:
                     for item in iter:
-                        if isinstance(item, BaseEvent):
+                        if isinstance(item, BaseEvent):  # pragma: no branch
                             self.logger.debug('ag-ui event: %s', item)
                             yield encoder.encode(item)
                 case _:  # pragma: no cover
@@ -481,11 +481,8 @@ async def _handle_agent_event(
                                     tool_call_id=agent_event.part.tool_call_id,
                                 ),
                             ),
+                            None,  # Signal continuation of the stream.
                         ]
-
-                        # TODO(steve): Merge with above list if we don't remove the local_tool_calls case.
-                        if tool_name:
-                            stream_ctx.part_ends.append(None)  # Signal continuation of the stream.
                     case ThinkingPart():  # pragma: no cover
                         # No equivalent AG-UI event yet.
                         pass
@@ -574,7 +571,7 @@ def _convert_history(messages: list[Message]) -> list[ModelMessage]:
                         ]
                     )
                 )
-            case DeveloperMessage():
+            case DeveloperMessage():  # pragma: no branch
                 # TODO(steve): Should these be handled differently?
                 result.append(ModelRequest(parts=[SystemPromptPart(content=msg.content)]))
 

pydantic_ai_slim/pydantic_ai/models/test.py

@@ -265,21 +265,21 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                     event = self._parts_manager.handle_tool_call_delta(
                         vendor_part_id=i, tool_name=part.tool_name, args='', tool_call_id=part.tool_call_id
                     )
-                    if event is not None:
+                    if event is not None:  # pragma: no branch
                         yield event
 
                     # Stream the args as JSON string in chunks.
                     args_json = pydantic_core.to_json(part.args).decode()
                     *chunks, last_chunk = args_json.split(',') if ',' in args_json else [args_json]
                     chunks = [f'{chunk},' for chunk in chunks] if chunks else []
-                    if last_chunk:
+                    if last_chunk:  # pragma: no branch
                         chunks.append(last_chunk)
 
                     for chunk in chunks:
                         event = self._parts_manager.handle_tool_call_delta(
                             vendor_part_id=i, tool_name=None, args=chunk, tool_call_id=part.tool_call_id
                         )
-                        if event is not None:
+                        if event is not None:  # pragma: no branch
                             yield event
                 else:
                     yield self._parts_manager.handle_tool_call_part(