@Test
public void testGetAncestor() {

    assertThat(EMPTY.getAncestor(0)).isNull();
    assertThat(SECTOR_REGION.getAncestor(0)).isNull();
    assertThat(INDUSTRY.getAncestor(0)).isEqualTo(SECTOR_REGION);
    assertThat(INDUSTRY.getAncestor(1)).isNull();
    assertThat(INDUSTRY_BE.getAncestor(0)).isEqualTo(SECTOR_REGION);
    assertThat(INDUSTRY_BE.getAncestor(1)).isEqualTo(INDUSTRY);
    assertThat(INDUSTRY_BE.getAncestor(2)).isNull();
}