public void Format_nullArgument_ArgumentNullException()
        {
            Exception error = new ArgumentNullException();

            IFormatProvider fp = new ToHexadecimalFormatProvider();
            string result = String.Format(fp, "{0:H}", null);

            Assert.AreEqual(error, result);
        }
        public void Format_100inHesSystem_64()
        {
            string ExpectedString = String.Format("{0:X}", 100);

            IFormatProvider fp = new ToHexadecimalFormatProvider();
            string result = String.Format(fp, "{0:H}", 100);

            Assert.AreEqual(ExpectedString, result);
        }