.push_slice(b"RUNE_TEST");

    for chunk in payload.chunks(bitcoin::blockdata::constants::MAX_SCRIPT_ELEMENT_SIZE) {
      let push: &bitcoin::script::PushBytes = chunk.try_into().unwrap();
      builder = builder.push_slice(push);
    }

    builder.into_script()
  }

  fn payload(transaction: &Transaction) -> Result<Option<Vec<u8>>> {
    for output in &transaction.output {
      let mut instructions = output.script_pubkey.instructions();

      if instructions.next().transpose()? != Some(Instruction::Op(opcodes::all::OP_RETURN)) {
        continue;
      }

      if instructions.next().transpose()? != Some(Instruction::PushBytes(b"RUNE_TEST".into())) {
        continue;
      }

      let mut payload = Vec::new();

      for result in instructions {
        if let Instruction::PushBytes(push) = result? {
          payload.extend_from_slice(push.as_bytes());
        }
      }

      return Ok(Some(payload));
    }

    Ok(None)
  }
}

#[cfg(test)]
mod tests {
  use {
    super::*,
    bitcoin::{locktime, script::PushBytes, ScriptBuf, TxOut},