@Test
public void testGetTotalExactMass_IMolecularFormula() throws Exception {

    IMolecularFormula formula = new MolecularFormula();
    IIsotope carb = builder.newInstance(IIsotope.class, "C");
    carb.setExactMass(12.00);
    IIsotope cl = builder.newInstance(IIsotope.class, "Cl");
    cl.setExactMass(34.96885268);
    formula.addIsotope(carb);
    formula.addIsotope(cl);
    double totalExactMass = MolecularFormulaManipulator.getTotalExactMass(formula);
    Assert.assertEquals(46.96885268, totalExactMass, 0.000001);
}