public void TestInvalidEra()
        {
            DateTimeFormatInfo info = new CultureInfo("en-us").DateTimeFormat;

            Assert.Throws<ArgumentOutOfRangeException>(() =>
            {
                info.GetAbbreviatedEraName(-1);
            });
            Assert.Throws<ArgumentOutOfRangeException>(() =>
            {
                info.GetAbbreviatedEraName(2);
            });
        }