message: add unit test for path serialisation
diff: @@ -185,6 +185,14 @@ mod tests {
  let got = key.encrypt(&dat[..]);
  assert_eq!(&expected[..], &got[..])
  }
  +
  + #[test]
  + fn unit2() {
  + let path = Path::new(vec![0,1]);
  + let expected = [0x9f, 0x00, 0x01, 0x0ff];
  + let cbor = path.cbor();
  + assert_eq!(&expected[..], &cbor[..])
  + }
  }
  #[cfg(test)]
  