public void FormatNonNumber()
        {
            NumberFormatter fmt = new NumberFormatter();

            Assert.Throws <ArgumentException>(() => fmt.Format("not a number"));
        }
        public void FormatNonNumber()
        {
            NumberFormatter fmt = new NumberFormatter();

            fmt.Format("not a number");
        }
        public void FormatNullValue()
        {
            NumberFormatter fmt = new NumberFormatter();

            Assert.Throws <ArgumentNullException>(() => fmt.Format(null));
        }
        public void FormatNullValue()
        {
            NumberFormatter fmt = new NumberFormatter();

            fmt.Format(null);
        }