@Test
public void testCompare_DifferentSymbol() throws Exception {

    SimpleAtomComparator comparator = new SimpleAtomComparator();
    IAtom a1 = builder.newInstance(IAtom.class, "C");
    IAtom a2 = builder.newInstance(IAtom.class, "O");
    // can't do less than correctly without hamcrest?
    Assert.assertTrue("oxygen should rank above carbon", comparator.compare(a1, a2) < 0);
    Assert.assertTrue("oxygen should rank above carbon (inverse)", comparator.compare(a2, a1) > 0);
}