@Test
public void testMaxLength() {

    int maxLength = 2;
    IntPredicate filter = i -> true;
    
    List<Tuple2id> result = recommender.getRecommendation(0, maxLength, filter).getIidxs();
    List<Tuple2id> expected = Arrays.asList(
            tuple(0, 6.0),
            tuple(1, 5.0)
    );
    
    assertEquals(expected, result);
}