import os

from app.rag import rerank


def test_rerank_disabled_is_stable(monkeypatch):
    monkeypatch.delenv("RAG_RERANKER_MODEL", raising=False)
    rows = [{"id": "a", "text": "第一"}, {"id": "b", "text": "第二"}]
    assert rerank.rerank(rows, "问题") == rows
    metric = rerank.last_metric()
    assert metric["fallback"] is True
    assert metric["reranked_count"] == 0


def test_rerank_local_model_missing_falls_back(monkeypatch, tmp_path):
    monkeypatch.setenv("RAG_RERANKER_MODEL", str(tmp_path / "missing"))
    rows = [{"id": "a", "text": "第一"}, {"id": "b", "text": "第二"}]
    assert rerank.rerank(rows, "问题") == rows
    assert rerank.last_metric()["fallback"] is True