@Test
public void testVerticalSum() {

    CrossTable sum = CrossTable.verticalSum(table, other);
    
    assertEquals(sum.getNumberOfRows(), 6);
    assertEquals(sum.getNumberOfColumns(), 6);
    assertEquals(sum.getRow(0).intent, bits(1, 2, 3, 4, 5));
    assertEquals(sum.getRow(3).intent, bits(4, 5));
    assertEquals(sum.getRow(5).intent, bits());
    
    assertEquals(table.getNumberOfRows(), 3);
    assertEquals(table.getRow(0).intent, bits(1, 2));
}