public void Write_8BE()
        {
            byte[] want = { 0x12, 0xAD, 0xBE, 0xEF, 0x98, 0x76, 0xAB, 0xCD };
            byte[] got;
            using (var os = new OtpOutputStream())
            {
                os.Write8BE(0x12ADBEEF9876ABCD);
                got = os.ToArray();
            }

            CollectionAssert.AreEqual(want, got);
        }