chore: import upstream snapshot with attribution

sdk-python/tests/test_langchain_messages_to_copilotkit.py

@@ -0,0 +1,138 @@
+"""Tests for langchain_messages_to_copilotkit assistant message emission.
+
+Covers the parentMessageId orphan bug where an `if content:` guard skipped
+emitting the assistant message when content was empty. Tool call entries
+reference their parent assistant message via parentMessageId, so the
+assistant message must always be emitted — even when content is empty
+(standard OpenAI behavior for tool-call-only responses).
+"""
+
+from langchain_core.messages import AIMessage, HumanMessage, ToolMessage
+
+from copilotkit.langgraph import langchain_messages_to_copilotkit
+
+
+def _convert_and_split(messages):
+    """Convert messages and split result into assistant vs tool-call entries."""
+    result = langchain_messages_to_copilotkit(messages)
+    assistant_msgs = [m for m in result if m.get("role") == "assistant"]
+    tool_call_msgs = [m for m in result if "parentMessageId" in m]
+    return result, assistant_msgs, tool_call_msgs
+
+
+class TestAssistantMessageAlwaysEmitted:
+    """The assistant message must always be present so tool call entries can
+    reference it via parentMessageId. Without it, tool calls are orphaned
+    and the frontend cannot reconstruct tool call rendering on reconnect."""
+
+    def test_ai_message_with_content_and_tool_calls(self):
+        """AIMessage with both content and tool_calls emits assistant + tool calls."""
+        messages = [
+            AIMessage(
+                id="ai-1",
+                content="Let me help with that.",
+                tool_calls=[
+                    {"id": "tc-1", "name": "get_help", "args": {"topic": "billing"}}
+                ],
+            ),
+        ]
+        _, assistant_msgs, tool_call_msgs = _convert_and_split(messages)
+
+        assert len(assistant_msgs) == 1
+        assert assistant_msgs[0]["id"] == "ai-1"
+        assert assistant_msgs[0]["content"] == "Let me help with that."
+
+        assert len(tool_call_msgs) == 1
+        assert tool_call_msgs[0]["parentMessageId"] == "ai-1"
+
+    def test_ai_message_with_empty_content_and_tool_calls(self):
+        """AIMessage with empty content (OpenAI-style) still emits the assistant message."""
+        messages = [
+            AIMessage(
+                id="ai-1",
+                content="",
+                tool_calls=[
+                    {"id": "tc-1", "name": "get_help", "args": {"topic": "billing"}}
+                ],
+            ),
+        ]
+        _, assistant_msgs, tool_call_msgs = _convert_and_split(messages)
+
+        assert len(assistant_msgs) == 1, (
+            "Assistant message must be emitted even with empty content"
+        )
+        assert assistant_msgs[0]["id"] == "ai-1"
+        assert assistant_msgs[0]["content"] == ""
+
+        assert len(tool_call_msgs) == 1
+        assert tool_call_msgs[0]["parentMessageId"] == "ai-1"
+
+    def test_ai_message_with_none_content_and_tool_calls(self):
+        """AIMessage with None content still emits the assistant message."""
+        msg = AIMessage(
+            id="ai-1",
+            content="",
+            tool_calls=[{"id": "tc-1", "name": "get_help", "args": {}}],
+        )
+        # Simulate None content (some models/edge cases)
+        msg.content = None  # type: ignore[assignment]
+
+        _, assistant_msgs, _ = _convert_and_split([msg])
+
+        assert len(assistant_msgs) == 1, (
+            "Assistant message must be emitted even with None content"
+        )
+        assert assistant_msgs[0]["content"] == ""
+
+    def test_no_orphaned_parent_message_ids(self):
+        """Every parentMessageId must reference an existing assistant message."""
+        messages = [
+            HumanMessage(id="h-1", content="help me"),
+            AIMessage(
+                id="ai-1",
+                content="",
+                tool_calls=[
+                    {"id": "tc-1", "name": "get_help", "args": {"topic": "billing"}},
+                    {"id": "tc-2", "name": "search", "args": {"query": "docs"}},
+                ],
+            ),
+            ToolMessage(id="tm-1", content="done", tool_call_id="tc-1"),
+            ToolMessage(id="tm-2", content="found", tool_call_id="tc-2"),
+        ]
+        result, _, tool_call_msgs = _convert_and_split(messages)
+
+        message_ids = {m["id"] for m in result if "role" in m}
+
+        for tc in tool_call_msgs:
+            assert tc["parentMessageId"] in message_ids, (
+                f"Tool call {tc['id']} has orphaned parentMessageId {tc['parentMessageId']}"
+            )
+
+    def test_ai_message_with_list_content_and_tool_calls(self):
+        """AIMessage with empty list content (Anthropic-style) still emits the assistant message."""
+        msg = AIMessage(
+            id="ai-1",
+            content="",
+            tool_calls=[{"id": "tc-1", "name": "get_help", "args": {}}],
+        )
+        # Anthropic models can return content as a list; empty list is falsy
+        msg.content = []  # type: ignore[assignment]
+
+        _, assistant_msgs, tool_call_msgs = _convert_and_split([msg])
+
+        assert len(assistant_msgs) == 1, (
+            "Assistant message must be emitted even with empty list content"
+        )
+        assert assistant_msgs[0]["content"] == ""
+
+        assert len(tool_call_msgs) == 1
+        assert tool_call_msgs[0]["parentMessageId"] == "ai-1"
+
+    def test_ai_message_without_tool_calls(self):
+        """Plain AIMessage (no tool calls) emits just the assistant message."""
+        messages = [AIMessage(id="ai-1", content="Hello!")]
+        result, _, _ = _convert_and_split(messages)
+
+        assert len(result) == 1
+        assert result[0]["role"] == "assistant"
+        assert result[0]["content"] == "Hello!"