@Test
public void testTotalTruth() {

    Metric<Double> scoreCalculator = new ROCAUC();
    LabelPairCursor<Double> cursor = new TestLabelPairCursor<>(
        Arrays.asList(1.0, 1.0, 1.0, 1.0, 1.0),
        Arrays.asList(1.0, 1.0, 1.0, 1.0, 1.0)
    );
    double score = scoreCalculator.score(cursor.iterator());
    assertEquals(Double.NaN, score, 1e-12);
}