test_trim_messages_mixed_content_with_partial() — langchain Function Reference

Source Code

libs/core/tests/unit_tests/messages/test_utils.py lines 593–629

def test_trim_messages_mixed_content_with_partial() -> None:
    messages = [
        AIMessage(
            content=[
                {"type": "text", "text": "First part of text."},
                {"type": "text", "text": "Second part that should be trimmed."},
            ]
        )
    ]
    messages_copy = [m.model_copy(deep=True) for m in messages]

    # Count total length of all text parts
    def count_text_length(msgs: list[BaseMessage]) -> int:
        total = 0
        for msg in msgs:
            if isinstance(msg.content, list):
                for block in msg.content:
                    if isinstance(block, dict) and block.get("type") == "text":
                        total += len(block["text"])
            elif isinstance(msg.content, str):
                total += len(msg.content)
        return total

    result = trim_messages(
        messages,
        max_tokens=20,  # Only allow first text block
        token_counter=count_text_length,
        strategy="first",
        allow_partial=True,
    )

    assert len(result) == 1
    assert len(result[0].content) == 1
    content = result[0].content[0]
    assert isinstance(content, dict)
    assert content["text"] == "First part of text."
    assert messages == messages_copy