public void AddNegativeFormulaToFormula()
{
ChemicalFormula formulaA = new ChemicalFormula("C2H3NO");
ChemicalFormula formulaB = new ChemicalFormula("C-1H-2");
ChemicalFormula formulaC = new ChemicalFormula("CHNO");
formulaA.Add(formulaB);
Assert.AreEqual(formulaA, formulaC);
}