@Test
public void updateToNPDPlus() {

    int[] cycle = new int[]{2, 4, 3, 1, 0, 5, 2};
    String[] symbs = new String[10];
    Arrays.fill(symbs, "");
    symbs[cycle[1]] = "NCN+";
    symbs[cycle[2]] = "N+=C";
    symbs[cycle[3]] = "N=+C";
    MmffAromaticTypeMapping.updateAromaticTypesInSixMemberRing(cycle, symbs);
    assertThat(symbs[cycle[1]], is("NPD+"));
    assertThat(symbs[cycle[2]], is("NPD+"));
    assertThat(symbs[cycle[3]], is("NPD+"));
}