test(chain): introduce tests for changing descriptors

crates/chain/tests/test_keychain_txout_index.rs

@@ -5,7 +5,7 @@ mod common;
 use bdk_chain::{
     collections::BTreeMap,
     indexed_tx_graph::Indexer,
-    keychain::{self, ChangeSet, DescriptorId, KeychainTxOutIndex},
+    keychain::{self, DescriptorId, KeychainTxOutIndex},
     Append, DescriptorExt,
 };
 
@@ -76,11 +76,11 @@ fn append_keychain_derivation_indices() {
     rhs_di.insert(descriptor_ids[1], 5); // value more than lhs desc 1
     lhs_di.insert(descriptor_ids[3], 4); // key doesn't exist in lhs
 
-    let mut lhs = ChangeSet {
+    let mut lhs = keychain::ChangeSet {
         keychains_added: BTreeMap::<(), _>::new(),
         last_revealed: lhs_di,
     };
-    let rhs = ChangeSet {
+    let rhs = keychain::ChangeSet {
         keychains_added: BTreeMap::<(), _>::new(),
         last_revealed: rhs_di,
     };
@@ -111,7 +111,7 @@ fn test_insert_different_desc_same_keychain() {
         ]
     );
 
-    let changeset = ChangeSet {
+    let changeset = keychain::ChangeSet {
         keychains_added: [(TestKeychain::External, internal_descriptor.clone())].into(),
         last_revealed: [].into(),
     };
@@ -125,7 +125,7 @@ fn test_insert_different_desc_same_keychain() {
         ]
     );
 
-    let changeset = ChangeSet {
+    let changeset = keychain::ChangeSet {
         keychains_added: [(TestKeychain::Internal, external_descriptor.clone())].into(),
         last_revealed: [].into(),
     };
@@ -158,7 +158,7 @@ fn test_set_all_derivation_indices() {
     .into();
     assert_eq!(
         txout_index.reveal_to_target_multi(&derive_to).1,
-        ChangeSet {
+        keychain::ChangeSet {
             keychains_added: BTreeMap::new(),
             last_revealed: last_revealed.clone()
         }
@@ -531,3 +531,67 @@ fn test_non_wildcard_derivations() {
         1,
     );
 }
+
+/// `::index_txout` should still index txouts with spks derived from descriptors without keychains.
+/// This includes properly refilling the lookahead for said descriptors.
+#[test]
+fn index_txout_after_changing_descriptor_under_keychain() {
+    let secp = bdk_chain::bitcoin::secp256k1::Secp256k1::signing_only();
+    let (desc_a, _) = Descriptor::<DescriptorPublicKey>::parse_descriptor(&secp, DESCRIPTORS[0])
+        .expect("descriptor 0 must be valid");
+    let (desc_b, _) = Descriptor::<DescriptorPublicKey>::parse_descriptor(&secp, DESCRIPTORS[1])
+        .expect("descriptor 1 must be valid");
+    let desc_id_a = desc_a.descriptor_id();
+
+    let mut txout_index = bdk_chain::keychain::KeychainTxOutIndex::<()>::new(10);
+
+    // Introduce `desc_a` under keychain `()` and replace the descriptor.
+    let _ = txout_index.insert_descriptor(desc_a.clone(), ());
+    let _ = txout_index.insert_descriptor(desc_b.clone(), ());
+
+    // Loop through spks in intervals of `lookahead` to create outputs with. We should always be
+    // able to index these outputs if `lookahead` is respected.
+    let spk_indices = [9, 19, 29, 39];
+    for i in spk_indices {
+        let spk_at_index = desc_a
+            .at_derivation_index(i)
+            .expect("must derive")
+            .script_pubkey();
+        let index_changeset = txout_index.index_txout(
+            // Use spk derivation index as vout as we just want an unique outpoint.
+            OutPoint::new(h!("mock_tx"), i as _),
+            &TxOut {
+                value: 10_000,
+                script_pubkey: spk_at_index,
+            },
+        );
+        assert_eq!(
+            index_changeset,
+            bdk_chain::keychain::ChangeSet {
+                keychains_added: BTreeMap::default(),
+                last_revealed: [(desc_id_a, i as u32)].into(),
+            },
+            "must always increase last active if impl respects lookahead"
+        );
+    }
+}
+
+#[test]
+fn insert_descriptor_no_change() {
+    let secp = Secp256k1::signing_only();
+    let (desc, _) =
+        Descriptor::<DescriptorPublicKey>::parse_descriptor(&secp, DESCRIPTORS[0]).unwrap();
+    let mut txout_index = KeychainTxOutIndex::<()>::default();
+    assert_eq!(
+        txout_index.insert_descriptor(desc.clone(), ()),
+        keychain::ChangeSet {
+            keychains_added: [((), desc.clone())].into(),
+            last_revealed: Default::default()
+        },
+    );
+    assert_eq!(
+        txout_index.insert_descriptor(desc.clone(), ()),
+        keychain::ChangeSet::default(),
+        "inserting the same descriptor for keychain should return an empty changeset",
+    );
+}