@Test
public void testMassDiff() throws Exception {

    String mdl = "deuterium.mol\n" + "\n" + "\n" + "  1  0  0  0  0                 1\n"
            + "    0.0000    0.0000    0.0000 H  +1  0  0  0  0\n";
    try (MDLReader reader = new MDLReader(new StringReader(mdl), Mode.STRICT)) {
        IAtomContainer mol = reader.read(new AtomContainer());
        IAtom atom = mol.getAtom(0);
        Assert.assertEquals(1, atom.getAtomicNumber().intValue());
        Assert.assertEquals(2, atom.getMassNumber().intValue());
    }
}