When I was originally working on this I thought there were issues converting Shift JIS to UTF-8 but it was just a behavior raised by the converter when encountering trash data. With correctly constructed Shift JIS (`"\xA6\xB5".force_encoding(Encoding::SHIFT_JIS)`) it passes. Is it worthwhile to try to test this case there the encoding is not UTF-8 and the transcoding to UTF-8 fails?