public RomanNumeralCalculator(
     ConvertToSingles convertToSingles,
     ConvertToRomanNumerals convertToRomanNumerals)
 {
     _convertToSingles       = convertToSingles;
     _convertToRomanNumerals = convertToRomanNumerals;
 }
        public void ConvertRomanNumeralToSingles(string romanNumeral, int expectedNumerOfI)
        {
            var sut    = new ConvertToSingles();
            var result = sut.Convert(romanNumeral);

            Assert.That(result.Length, Is.EqualTo(expectedNumerOfI));
        }