@Test(expected = IllegalArgumentException.class)
public void hydrogenCountMustBeDefined() {

    IAtomContainer container = new AtomContainer();
    container.addAtom(new Atom("C"));
    container.addAtom(new Atom("H"));
    container.addAtom(new Atom("H"));
    container.addAtom(new Atom("H"));
    container.addAtom(new Atom("H"));
    container.addBond(0, 1, SINGLE);
    container.addBond(0, 2, SINGLE);
    container.addBond(0, 3, SINGLE);
    container.addBond(0, 4, SINGLE);
    container.getAtom(0).setImplicitHydrogenCount(null);
    INSTANCE.symbolicTypes(container);
}