Merge bitcoindevkit/bdk#1335: fix(chain): tx_graph::ChangeSet::is_empty

13ab5a835d59341e387fbbefec12fe4f48e5f3c8 chore(chain): Improve TxGraph::ChangeSet docs (LLFourn)
dbbd51424284a960a95c3801b02dc1973322725f fix(chain)!: rm duplicate `is_empty` method in tx graph changeset (志宇)
ae00e1ee7b95c622fc3992c0804dd4b4517efc7b fix(chain): tx_graph::ChangeSet::is_empty (LLFourn)

Pull request description:

  🙈

  ### Changelog notice

  - Fix bug in `tx_graph::ChangeSet::is_empty` where is returns true even when it wasn't empty

  ### 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

  #### Bugfixes:

  * [ ] This pull request breaks the existing API
  * [x] I've added tests to reproduce the issue which are now passing

ACKs for top commit:
  LLFourn:
    Self-ACK: 13ab5a835d59341e387fbbefec12fe4f48e5f3c8
  evanlinjin:
    ACK 13ab5a835d59341e387fbbefec12fe4f48e5f3c8

Tree-SHA512: b9f1f17fd2ed0f8e2337a8033e1cbd3e9f15b1ad4b32da3f0eb73a30913d6798e7a08d6b297d93bd08c2e1c388226e97648650ac636846b2c7aa95c3bcefbcfd

crates/chain/src/tx_graph.rs

@@ -40,20 +40,23 @@
 //! # use bdk_chain::example_utils::*;
 //! # use bitcoin::Transaction;
 //! # let tx_a = tx_from_hex(RAW_TX_1);
-//! let mut graph: TxGraph = TxGraph::default();
+//! let mut tx_graph: TxGraph = TxGraph::default();
-//! let mut another_graph: TxGraph = TxGraph::default();
 //!
 //! // insert a transaction
-//! let changeset = graph.insert_tx(tx_a);
+//! let changeset = tx_graph.insert_tx(tx_a);
 //!
-//! // the resulting changeset can be applied to another tx graph
+//! // We can restore the state of the `tx_graph` by applying all
-//! another_graph.apply_changeset(changeset);
+//! // the changesets obtained by mutating the original (the order doesn't matter).
+//! let mut restored_tx_graph: TxGraph = TxGraph::default();
+//! restored_tx_graph.apply_changeset(changeset);
+//!
+//! assert_eq!(tx_graph, restored_tx_graph);
 //! ```
 //!
-//! A [`TxGraph`] can also be updated with another [`TxGraph`].
+//! A [`TxGraph`] can also be updated with another [`TxGraph`] which merges them together.
 //!
 //! ```
-//! # use bdk_chain::BlockId;
+//! # use bdk_chain::{Append, BlockId};
 //! # use bdk_chain::tx_graph::TxGraph;
 //! # use bdk_chain::example_utils::*;
 //! # use bitcoin::Transaction;
@@ -1212,11 +1215,6 @@ impl<A> Default for ChangeSet<A> {
 }
 
 impl<A> ChangeSet<A> {
-    /// Returns true if the [`ChangeSet`] is empty (no transactions or txouts).
-    pub fn is_empty(&self) -> bool {
-        self.txs.is_empty() && self.txouts.is_empty()
-    }
-
     /// Iterates over all outpoints contained within [`ChangeSet`].
     pub fn txouts(&self) -> impl Iterator<Item = (OutPoint, &TxOut)> {
         self.txs

crates/chain/tests/test_tx_graph.rs

@@ -213,7 +213,8 @@ fn insert_tx_graph_doesnt_count_coinbase_as_spent() {
     };
 
     let mut graph = TxGraph::<()>::default();
-    let _ = graph.insert_tx(tx);
+    let changeset = graph.insert_tx(tx);
+    assert!(!changeset.is_empty());
     assert!(graph.outspends(OutPoint::null()).is_empty());
     assert!(graph.tx_spends(Txid::all_zeros()).next().is_none());
 }
@@ -289,7 +290,7 @@ fn insert_tx_displaces_txouts() {
         }],
     };
 
-    let _ = tx_graph.insert_txout(
+    let changeset = tx_graph.insert_txout(
         OutPoint {
             txid: tx.txid(),
             vout: 0,
@@ -300,6 +301,8 @@ fn insert_tx_displaces_txouts() {
         },
     );
 
+    assert!(!changeset.is_empty());
+
     let _ = tx_graph.insert_txout(
         OutPoint {
             txid: tx.txid(),
@@ -653,7 +656,8 @@ fn test_walk_ancestors() {
     ]);
 
     [&tx_a0, &tx_b1].iter().for_each(|&tx| {
-        let _ = graph.insert_anchor(tx.txid(), tip.block_id());
+        let changeset = graph.insert_anchor(tx.txid(), tip.block_id());
+        assert!(!changeset.is_empty());
     });
 
     let ancestors = [
@@ -1027,10 +1031,12 @@ fn test_changeset_last_seen_append() {
             last_seen: original_ls.map(|ls| (txid, ls)).into_iter().collect(),
             ..Default::default()
         };
+        assert!(!original.is_empty() || original_ls.is_none());
         let update = ChangeSet::<()> {
             last_seen: update_ls.map(|ls| (txid, ls)).into_iter().collect(),
             ..Default::default()
         };
+        assert!(!update.is_empty() || update_ls.is_none());
 
         original.append(update);
         assert_eq!(