satpoint(1, 0),
        BTreeMap::from([(satpoint(1, 500), inscription_id(1))]),
        utxos.into_iter().collect(),
        BTreeSet::new(),
        recipient(),
        [change(0), change(1)],
        FeeRate::try_from(1.0).unwrap(),
        Target::Postage,
      )
      .build_transaction(),
      Err(Error::UtxoContainsAdditionalInscription {
        outgoing_satpoint: satpoint(1, 0),
        inscribed_satpoint: satpoint(1, 500),
        inscription_id: inscription_id(1),
      })
    )
  }

  #[test]
  fn build_transaction_with_custom_fee_rate() {
    let utxos = vec![(outpoint(1), Amount::from_sat(10_000))];

    let fee_rate = FeeRate::try_from(17.3).unwrap();

    let transaction = TransactionBuilder::new(
      satpoint(1, 0),
      BTreeMap::from([(satpoint(1, 0), inscription_id(1))]),
      utxos.into_iter().collect(),
      BTreeSet::new(),
      recipient(),
      [change(0), change(1)],
      fee_rate,
      Target::Postage,
    )
    .build_transaction()
    .unwrap();

    let fee =