def test_mean_underprediction_unweighted_single():
y_pred = [0]
y_true = [1]
result = metrics._mean_underprediction(y_true, y_pred)
assert result == 1
def test_mean_underprediction_unweighted():
y_pred = [0, 1, 1, 3, 4]
y_true = [1, 1, 5, 0, 2]
result = metrics._mean_underprediction(y_true, y_pred)
assert result == 1
def test_mean_underprediction_weighted_single():
y_pred = [0]
y_true = [42]
weight = [2]
result = metrics._mean_underprediction(y_true, y_pred, weight)
assert result == 42
def test_mean_underprediction_weighted():
y_pred = [0, 1, 5, 3, 1]
y_true = [1, 1, 2, 0, 2]
weight = [4, 1, 2, 2, 1]
result = metrics._mean_underprediction(y_true, y_pred, weight)
assert result == 0.5