Merge #393: refactor(wallet)!: Remove Wallet::cancel_tx function

1854b8e cleanup(wallet)!: remove cancel_tx function (Steve Myers)

Pull request description:

  ### Description

  Per discussion in team chat today I'm removing the `Wallet::cancel_tx` function because it's name is misleading and the `Wallet::mark_unused` function can be used to accomplish the same function.

  closes #326 and closes #212 and closes #41

  ### Notes to the reviewers

  This is an example of how to use `mark_unused` instead of `cancel_tx`

  ```rust
  /// This marks as unused the change addresses used when creating a tx so they can be used in future transactions.
  for txout in &tx.output {
      if let Some((keychain, index)) = txout_index.index_of_spk(txout.script_pubkey.clone()) {
          // NOTE: unmark_used will **not** make something unused if it has actually been used
          // by a tx in the tracker. It only removes the superficial marking.
          wallet.unmark_used(*keychain, *index);
      }
  }
  ```

  ### Changelog notice

  - BREAKING: Remove Wallet::cancel_tx function. Use Wallet::unmark_used instead

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `just p` before pushing

  #### Bugfixes:

  * [x] This pull request breaks the existing API
  * [ ] I've added tests to reproduce the issue which are now passing
  * [x] I'm linking the issue being fixed by this PR

ACKs for top commit:
  ValuedMammal:
    ACK 1854b8e

Tree-SHA512: c5fe988c61591267ce4c96fa005355d30a24c006431e60b276ab4a18c0a7be336a53f6c9800b43ab3e915dcb5c1847827e624854c56c14039caf54df4d456758

Author: ValuedMammal

src/wallet/mod.rs

@@ -1965,21 +1965,6 @@ impl Wallet {
             .0
     }
 
-    /// Informs the wallet that you no longer intend to broadcast a tx that was built from it.
-    ///
-    /// This frees up the change address used when creating the tx for use in future transactions.
-    // TODO: Make this free up reserved utxos when that's implemented
-    pub fn cancel_tx(&mut self, tx: &Transaction) {
-        let txout_index = &mut self.tx_graph.index;
-        for txout in &tx.output {
-            if let Some((keychain, index)) = txout_index.index_of_spk(txout.script_pubkey.clone()) {
-                // NOTE: unmark_used will **not** make something unused if it has actually been used
-                // by a tx in the tracker. It only removes the superficial marking.
-                txout_index.unmark_used(*keychain, *index);
-            }
-        }
-    }
-
     fn get_descriptor_for_txout(&self, txout: &TxOut) -> Option<DerivedDescriptor> {
         let &(keychain, child) = self
             .tx_graph

tests/wallet.rs

@@ -2768,77 +2768,6 @@ fn test_keychains_with_overlapping_spks() {
     assert_eq!(wallet.balance().confirmed, Amount::from_sat(58000));
 }
 
-#[test]
-/// The wallet should re-use previously allocated change addresses when the tx using them is
-/// cancelled
-fn test_tx_cancellation() {
-    macro_rules! new_tx {
-        ($wallet:expr) => {{
-            let addr = Address::from_str("2N4eQYCbKUHCCTUjBJeHcJp9ok6J2GZsTDt")
-                .unwrap()
-                .assume_checked();
-            let mut builder = $wallet.build_tx();
-            builder.add_recipient(addr.script_pubkey(), Amount::from_sat(10_000));
-
-            let psbt = builder.finish().unwrap();
-
-            psbt
-        }};
-    }
-
-    let (mut wallet, _) = get_funded_wallet(get_test_wpkh(), get_test_tr_single_sig_xprv());
-
-    let psbt1 = new_tx!(wallet);
-    let change_derivation_1 = psbt1
-        .unsigned_tx
-        .output
-        .iter()
-        .find_map(|txout| wallet.derivation_of_spk(txout.script_pubkey.clone()))
-        .unwrap();
-    assert_eq!(change_derivation_1, (KeychainKind::Internal, 0));
-
-    let psbt2 = new_tx!(wallet);
-
-    let change_derivation_2 = psbt2
-        .unsigned_tx
-        .output
-        .iter()
-        .find_map(|txout| wallet.derivation_of_spk(txout.script_pubkey.clone()))
-        .unwrap();
-    assert_eq!(change_derivation_2, (KeychainKind::Internal, 1));
-
-    wallet.cancel_tx(&psbt1.extract_tx().expect("failed to extract tx"));
-
-    let psbt3 = new_tx!(wallet);
-    let change_derivation_3 = psbt3
-        .unsigned_tx
-        .output
-        .iter()
-        .find_map(|txout| wallet.derivation_of_spk(txout.script_pubkey.clone()))
-        .unwrap();
-    assert_eq!(change_derivation_3, (KeychainKind::Internal, 0));
-
-    let psbt3 = new_tx!(wallet);
-    let change_derivation_3 = psbt3
-        .unsigned_tx
-        .output
-        .iter()
-        .find_map(|txout| wallet.derivation_of_spk(txout.script_pubkey.clone()))
-        .unwrap();
-    assert_eq!(change_derivation_3, (KeychainKind::Internal, 2));
-
-    wallet.cancel_tx(&psbt3.extract_tx().expect("failed to extract tx"));
-
-    let psbt3 = new_tx!(wallet);
-    let change_derivation_4 = psbt3
-        .unsigned_tx
-        .output
-        .iter()
-        .find_map(|txout| wallet.derivation_of_spk(txout.script_pubkey.clone()))
-        .unwrap();
-    assert_eq!(change_derivation_4, (KeychainKind::Internal, 2));
-}
-
 #[test]
 fn test_thread_safety() {
     fn thread_safe<T: Send + Sync>() {}