@Test
public void testCalculate_IronOxide() throws Exception {

    ISubstance material = new Substance();
    material.addAtomContainer(
        MolecularFormulaManipulator.getAtomContainer(
            "Fe3O4", DefaultChemObjectBuilder.getInstance()
        )
    );
    DescriptorValue value = descriptor.calculate(material);
    Assert.assertNotNull(value);
    IDescriptorResult result = value.getValue();
    Assert.assertNotNull(result);
    Assert.assertEquals(4, ((IntegerResult)result).intValue());
}