public void ShouldReturnFormulaWithZeroesForInvalidInputs()
        {
            var args = new String[] { "1", "a", "3", "4", "b", "6", "7", "8", "9", "10", "111", "12" };

            sut.ParseList(args);

            Assert.That(sut.GetNumCount(), Is.EqualTo(12));
            Assert.That(sut.GetFormula(), Is.EqualTo("1+0+3+4+0+6+7+8+9+10+111+12"));
        }