public void Writing()
        {
            var attachment = new CalendarAttachment()
            {
                ContentType = "audio/basic",
                Uri = "ftp://example.com/pub/sounds/bell-01.aud"
            };
            Assert.AreEqual("ATTACH;FMTTYPE=audio/basic:ftp://example.com/pub/sounds/bell-01.aud", attachment.ToString());

            attachment = new CalendarAttachment()
            {
                Uri = "CID:[email protected]"
            };
            Assert.AreEqual("ATTACH:CID:[email protected]", attachment.ToString());

            attachment = new CalendarAttachment()
            {
                ContentType = "text/plain",
                Content = Encoding.ASCII.GetBytes("The quick brown fox jumps over the lazy dog.")
            };
            Assert.AreEqual("ATTACH;FMTTYPE=text/plain;ENCODING=BASE64;VALUE=BINARY:VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wcyBvdmVyIHRoZSBsYXp5IGRvZy4=", attachment.ToString());
        }