Merge #1109: Further improve unconfirmed tx conflict resolution

afbf83c chain(fix): conflict resolution for txs with same last_seen (Wei Chen)

Pull request description:

  ### Description

  Fixes #1102. If a conflicting tx has the same `last_seen`, then we check lexicographical sorting of txids.

  ### Notes to the reviewers

  The tests for this fix exist in the `TxTemplate` structure in #1064 which may need to be merged first.

  ### 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 `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  danielabrozzoni:
    ACK afbf83c

Tree-SHA512: 91b8fbff305b715247501b861ab7ea9e9d9ef99248b05d14e01aacf7e64ad7826f35773e8998cf421dbd04f663714026084c6e817ac5365bce4844c8ea3b7e3f

crates/chain/src/tx_graph.rs

@@ -789,6 +789,12 @@ impl<A: Anchor> TxGraph<A> {
                 if conflicting_tx.last_seen_unconfirmed > tx_last_seen {
                     return Ok(None);
                 }
+                if conflicting_tx.last_seen_unconfirmed == *last_seen
+                    && conflicting_tx.txid() > tx.txid()
+                {
+                    // Conflicting tx has priority if txid of conflicting tx > txid of original tx
+                    return Ok(None);
+                }
             }
         }
 

crates/chain/tests/test_tx_graph_conflicts.rs

@@ -50,10 +50,10 @@ fn test_tx_conflict_handling() {
             tx_templates: &[
                 TxTemplate {
                     tx_name: "tx1",
-                    inputs: &[TxInTemplate::Bogus],
                     outputs: &[TxOutTemplate::new(40000, Some(0))],
                     anchors: &[block_id!(1, "B")],
                     last_seen: None,
+                    ..Default::default()
                 },
                 TxTemplate {
                     tx_name: "tx_conflict_1",
@@ -70,14 +70,12 @@ fn test_tx_conflict_handling() {
                     ..Default::default()
                 },
             ],
-            // correct output if filtered by fee rate: tx1, tx_conflict_1
-            exp_chain_txs: HashSet::from(["tx1", "tx_conflict_1", "tx_conflict_2"]),
-            exp_chain_txouts: HashSet::from([("tx1", 0), ("tx_conflict_1", 0), ("tx_conflict_2", 0)]),
-            // correct output if filtered by fee rate: tx_conflict_1
-            exp_unspents: HashSet::from([("tx_conflict_1", 0), ("tx_conflict_2", 0)]),
+            exp_chain_txs: HashSet::from(["tx1", "tx_conflict_2"]),
+            exp_chain_txouts: HashSet::from([("tx1", 0), ("tx_conflict_2", 0)]),
+            exp_unspents: HashSet::from([("tx_conflict_2", 0)]),
             exp_balance: Balance {
                 immature: 0,
-                trusted_pending: 50000, // correct output if filtered by fee rate: 20000
+                trusted_pending: 30000,
                 untrusted_pending: 0,
                 confirmed: 0,
             },