public void to_decimal()
        {
            Assert.Throws <ArgumentNullException>(() => ConvertExtensions.Decimal(null, new object()));

            Assert.Null(Convert.To.Decimal(null));
            Assert.Equal(decimal.MinValue, Convert.To.Decimal(decimal.MinValue));
            Assert.Equal(decimal.MinValue, Convert.To.Decimal(decimal.MinValue.ToString(CultureInfo.InvariantCulture)));
            Assert.Null(Convert.To.Decimal(new object()));
        }