public void ShouldRaiseError(string numeral)
{
Assert.ThrowsException <ArgumentException>(() => NumeralConverter.ConvertRomanNumeralToInt(numeral));
}
public void ShouldConvertProperly(string numeral, int expected)
{
var result = NumeralConverter.ConvertRomanNumeralToInt(numeral);
Assert.AreEqual(expected, result);
}