"""572-2 B04 유입 캐시 상한 — 프로젝트 넷만 남김 · 다시 쓴 것은 뒤로."""

import numpy as np

from B04_PreProcess import B04_PreProcess_Router_Inflow as inflow


def _write(path):
    np.savez(
        path,
        x_min=0.0,
        y_max=0.0,
        cell_m=1.0,
        n_rows=1,
        n_cols=1,
        road_slot=np.zeros(1),
        road_chainage=np.zeros(1),
        path_length=np.zeros(1),
    )


def test_cache_keeps_four_recent(tmp_path, monkeypatch):
    monkeypatch.setattr(inflow, "_routing_path", lambda stored: tmp_path / f"{stored}.npz")
    inflow._CACHE.clear()
    for name in "abcde":
        _write(tmp_path / f"{name}.npz")
    for name in "abcd":
        inflow._load_routing(name)
    inflow._load_routing("a")  # 다시 씀 → 맨 뒤
    inflow._load_routing("e")
    assert list(inflow._CACHE) == ["c", "d", "a", "e"]