"""Exercise the comparison snippet when the optional LangGraph library exists."""

from pathlib import Path

import pytest


@pytest.mark.parametrize(
    ("text", "expected_report"),
    [(" Notes ", "# Report\n\nNotes"), ("   ", "")],
)
def test_langgraph_comparison_routes_updated_state(
    text: str, expected_report: str
) -> None:
    """Check the rendered example without making LangGraph a product dependency."""
    pytest.importorskip("langgraph.graph")
    manuscript = (
        Path(__file__).resolve().parents[2]
        / "docs/thesis/system-design-implementation.md"
    ).read_text(encoding="utf-8")
    section = manuscript.split("<!-- langgraph-comparison -->", 1)[1]
    snippet = section.split("```python\n", 1)[1].split("```", 1)[0]
    namespace = {}
    # This is trusted repository prose, executed exactly as displayed.
    exec(compile(snippet, "thesis-langgraph-example", "exec"), namespace)
    result = namespace["graph"].invoke({"text": text, "report": ""})
    assert result["text"] == text.strip()
    assert result["report"] == expected_report