let () =
  let open Json in
  let check jsont s =
    let encode v = encode jsont v |> Result.get_ok in
    let decode v = decode jsont v |> Result.get_ok in
    let ts = decode s in
    let s' = encode ts in
    let ts' = decode s' in
    let s'' = encode ts' in
    assert (String.equal s' s'')
  in
  let check_bad jsont s =
    let decode = decode jsont in
    assert (Result.is_error (decode s))
  in
  check Timestamp.jsont {|{"t_s": 123456780}|};
  check Timestamp.jsont {|{"t_s": "never"}|};
  check_bad Timestamp.jsont {|{"t_s": "123456780"}|};
  check_bad Timestamp.jsont {|{"t_s": "agagou"}|};
  ()