in src/crc.rs [143:153]
fn test_crc_write() {
let mut buf = vec![0; 16];
let write_buf = vec![123; 16];
let mut slice = buf.as_mut_slice();
let mut crc_writer = CRC64Writer::new(&mut slice);
crc_writer.write_all(&write_buf.as_slice()).unwrap();
crc_writer.flush().unwrap();
assert_eq!(crc_writer.checksum(), 0x29D5_3572_1632_6566);
assert_eq!(crc_writer.checksum(), crc_writer.crc64);
}