import numpy as np

from scripts.run_pairwise_unary_stack import score_metrics


def test_stacked_metrics_compute_per_class_accuracy_and_pair_pass():
    y = np.array([0, 1, 0, 1], dtype=np.int8)
    pred = np.array([0, 1, 1, 0], dtype=np.int8)
    result = score_metrics(y, pred, pair_count=2)
    assert result["accuracy"] == 0.5
    assert result["safe_accuracy"] == 0.5
    assert result["vulnerable_accuracy"] == 0.5
    assert result["pair_pass_at_1"] == 0.5
    assert result["pair_pass_wilson_95"] is not None


def test_stacked_metrics_track_single_class_collapse():
    y = np.array([0, 1, 0, 1], dtype=np.int8)
    pred = np.zeros(4, dtype=np.int8)
    result = score_metrics(y, pred, pair_count=2)
    assert result["safe_accuracy"] == 1.0
    assert result["vulnerable_accuracy"] == 0.0
    assert result["predicted_vulnerable_fraction"] == 0.0
    assert result["pair_pass_at_1"] == 0.0