test_get_buffer_string_xml_tool_calls_preferred_over_function_call() — langchain Function Reference

Source Code

libs/core/tests/unit_tests/messages/test_utils.py lines 2147–2170

def test_get_buffer_string_xml_tool_calls_preferred_over_function_call() -> None:
    """Test that `tool_calls` takes precedence over legacy `function_call` in XML."""
    messages = [
        AIMessage(
            content="Calling tools",
            tool_calls=[
                {
                    "name": "modern_tool",
                    "args": {"key": "value"},
                    "id": "call_3",
                    "type": "tool_call",
                }
            ],
            additional_kwargs={
                "function_call": {"name": "legacy_function", "arguments": "{}"}
            },
        ),
    ]
    result = get_buffer_string(messages, format="xml")
    assert "modern_tool" in result
    assert "legacy_function" not in result
    # Should use tool_call element, not function_call
    assert "<tool_call" in result
    assert "<function_call" not in result