bench: added txout_index_lookahead test

Author: notmandatory

crates/chain/benches/txout_index_lookahead.rs

@@ -0,0 +1,24 @@
+use bitcoin::key::Secp256k1;
+use criterion::{criterion_group, criterion_main, Criterion};
+use miniscript::{Descriptor, DescriptorPublicKey};
+use bdk_chain::{DescriptorExt, Indexer};
+use bdk_chain::keychain_txout::{ChangeSet, KeychainTxOutIndex};
+
+#[test]
+fn cache_and_load_spks(target_index: u32) {
+    const DESC: &str = "tr([ab28dc00/86h/1h/0h]tpubDCdDtzAMZZrkwKBxwNcGCqe4FRydeD9rfMisoi7qLdraG79YohRfPW4YgdKQhpgASdvh612xXNY5xYzoqnyCgPbkpK4LSVcH5Xv4cK7johH/0/*)";
+
+    let (desc, _) =
+        <Descriptor<DescriptorPublicKey>>::parse_descriptor(&Secp256k1::new(), DESC).unwrap();
+    let mut txout_index = KeychainTxOutIndex::new(0, false);
+    txout_index.insert_descriptor((), desc.clone()).unwrap();
+    let lookahead_changeset = txout_index.lookahead_to_target((), target_index);
+    dbg!(&lookahead_changeset);
+}
+
+fn criterion_benchmark(c: &mut Criterion) {
+    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);