satpoint(2, 0),
      BTreeMap::new(),
      vec![(outpoint(1), Amount::from_sat(4))]
        .into_iter()
        .collect(),
      BTreeSet::new(),
      recipient(),
      [change(0), change(1)],
      FeeRate::try_from(1.0).unwrap(),
      Target::Postage,
    )
    .build()
    .unwrap();
  }

  #[test]
  #[should_panic(expected = "invariant: outgoing sat is contained in utxos")]
  fn invariant_satpoint_offset_is_contained_in_utxos() {
    TransactionBuilder::new(
      satpoint(1, 4),
      BTreeMap::new(),
      vec![(outpoint(1), Amount::from_sat(4))]
        .into_iter()
        .collect(),
      BTreeSet::new(),
      recipient(),
      [change(0), change(1)],
      FeeRate::try_from(1.0).unwrap(),
      Target::Postage,
    )
    .build()
    .unwrap();
  }

  #[test]
  #[should_panic(expected = "invariant: inputs spend outgoing sat")]
  fn invariant_inputs_spend_sat() {
    TransactionBuilder::new(
      satpoint(1, 2),
      BTreeMap::new(),
      vec![(outpoint(1), Amount::from_sat(5))]
        .into_iter()