from train_sft import _is_better_eval, _sibling


def test_sibling_last_best():
    assert _sibling("ckpts/k3_sft.pt", "_last") == "ckpts/k3_sft_last.pt"
    assert _sibling("ckpts/k3_sft.pt", "_best") == "ckpts/k3_sft_best.pt"


def test_best_prefers_success_then_chrf():
    assert _is_better_eval(1.0, 70.0, 0.95, 90.0)
    assert not _is_better_eval(0.95, 99.0, 1.0, 70.0)
    assert _is_better_eval(1.0, 91.0, 1.0, 81.0)
    assert not _is_better_eval(1.0, 70.0, 1.0, 81.0)