Adds test inserting anchor without tx

Test inserting anchors without the corresponding transaction
and testing the recoverability of the transaction graph

Partially fixes "More tests for IndexedTxGraph and TxGraph bitcoindevkit#958"
bitcoindevkit#958

crates/chain/tests/common/mod.rs

@@ -1,6 +1,6 @@
 #[allow(unused_macros)]
 macro_rules! h {
-    ($index:literal) => {{
+    ($index:expr) => {{
         bitcoin::hashes::Hash::hash($index.as_bytes())
     }};
 }

crates/chain/tests/test_tx_graph.rs

@@ -822,3 +822,95 @@ fn test_additions_last_seen_append() {
         );
     }
 }
+
+/// Inserting anchors without the corresponding transaction
+/// and testing the recoverability of the transaction graph
+#[test]
+fn test_inserting_anchor_without_tx() {
+    let mut graph = TxGraph::<ConfirmationHeightAnchor>::default();
+    let mut graph_recovered = graph.clone();
+    let txs = (0..5).map(common::new_tx).collect::<Vec<_>>();
+    let chain: LocalChain = (0..5)
+        .map(|i| (i, h!(i.to_string())))
+        .collect::<BTreeMap<u32, BlockHash>>()
+        .into();
+    let anchors = (0..5)
+        .map(|i| ConfirmationHeightAnchor {
+            anchor_block: BlockId {
+                height: i,
+                hash: *chain.blocks().get(&i).unwrap(),
+            },
+            confirmation_height: 0,
+        })
+        .collect::<Vec<_>>();
+
+    let mut anchor_additions = Additions::default();
+    for i in 0..3 {
+        let additions = graph.insert_anchor(txs[i].txid(), anchors[i]);
+        anchor_additions.append(additions);
+    }
+
+    // Additions should only include the Anchor for the Tx-Block 0, 1 and 2
+    assert_eq!(
+        anchor_additions,
+        Additions {
+            tx: Default::default(),
+            txout: Default::default(),
+            anchors: BTreeSet::from([
+                (anchors[0], txs[0].txid()),
+                (anchors[1], txs[1].txid()),
+                (anchors[2], txs[2].txid()),
+            ]),
+            last_seen: Default::default(),
+        }
+    );
+
+    // graph should be recoverable from additions
+    graph_recovered.apply_additions(anchor_additions);
+    assert_eq!(graph, graph_recovered);
+
+    // Check whether Anchors are part of TxGraph
+    for i in 0..3 {
+        assert!(graph.all_anchors().contains(&(anchors[i], txs[i].txid())));
+    }
+
+    let mut tx_additions = Additions::default();
+    for tx in &txs[1..] {
+        let additions = graph.insert_tx(tx.clone());
+        assert_eq!(
+            additions,
+            Additions {
+                tx: BTreeSet::from([tx.clone()]),
+                txout: Default::default(),
+                anchors: BTreeSet::default(),
+                last_seen: Default::default(),
+            }
+        );
+        tx_additions.append(additions);
+    }
+
+    // graph should be recoverable from additions
+    graph_recovered.apply_additions(tx_additions);
+    assert_eq!(graph, graph_recovered);
+
+    // Transactions 0, 1 and 3 should have an Anchor
+    for i in 0..3 {
+        assert_eq!(
+            graph
+                .get_chain_position(&chain, chain.tip().unwrap(), txs[i].txid())
+                .unwrap(),
+            ObservedAs::Confirmed(&anchors[i])
+        );
+    }
+
+    // Transactions 4 and 5 should not have an Anchor
+    for tx in txs.iter().take(5).skip(4) {
+        assert_eq!(
+            graph
+                .try_get_chain_position(&chain, chain.tip().unwrap(), tx.txid())
+                .unwrap()
+                .unwrap(),
+            ObservedAs::Unconfirmed(0)
+        );
+    }
+}