witness: Witness::new(),
        })
        .collect(),
      output: self
        .outputs
        .iter()
        .map(|(address, amount)| TxOut {
          value: amount.to_sat(),
          script_pubkey: address.script_pubkey(),
        })
        .collect(),
    };

    assert_eq!(
      self
        .amounts
        .iter()
        .filter(|(outpoint, amount)| *outpoint == &self.outgoing.outpoint
          && self.outgoing.offset < amount.to_sat())
        .count(),
      1,
      "invariant: outgoing sat is contained in utxos"
    );

    assert_eq!(
      transaction
        .input
        .iter()
        .filter(|tx_in| tx_in.previous_output == self.outgoing.outpoint)
        .count(),
      1,
      "invariant: inputs spend outgoing sat"
    );

    let mut sat_offset = 0;
    let mut found = false;
    for tx_in in &transaction.input {
      if tx_in.previous_output == self.outgoing.outpoint {
        sat_offset += self.outgoing.offset;
        found = true;
        break;
      } else {