@Test
public void testDifference() {

    IChemObject atom1 = mock(IChemObject.class);
    IChemObject atom2 = mock(IChemObject.class);
    when(atom1.getFlags()).thenReturn(new boolean[]{false, false, false});
    when(atom2.getFlags()).thenReturn(new boolean[]{false, true, false});
    IDifference difference = ChemObjectDiff.difference(atom1, atom2);
    Assert.assertNotNull(difference);
}