Add Sorting Logic for Inputs with creation_sequence (#50)

* Update FIFO selection to prioritize OutputGroups with None sequence

* Prioritize OutputGroups with sequence numbers

* Fix Clippy warning by using  instead of

* Check inputs with creation_sequence are sorted

src/lib.rs

@@ -316,6 +316,8 @@ pub fn select_coin_fifo(
  .filter(|(_, og)| og.creation_sequence.is_some())
  .collect();
 
+ sorted_inputs.sort_by(|a, b| a.1.creation_sequence.cmp(&b.1.creation_sequence));
+
  let mut inputs_without_sequence: Vec<_> = inputs
  .iter()
  .enumerate()
@@ -1213,6 +1215,72 @@ mod test {
  test_insufficient_funds();
  }
 
+ #[test]
+ fn test_fifo_with_none_and_sequence() {
+ let inputs = vec![
+ OutputGroup {
+ value: 1000,
+ weight: 100,
+ input_count: 1,
+ is_segwit: false,
+ creation_sequence: Some(1),
+ },
+ OutputGroup {
+ value: 2000,
+ weight: 200,
+ input_count: 1,
+ is_segwit: false,
+ creation_sequence: None, // No sequence
+ },
+ OutputGroup {
+ value: 3000,
+ weight: 300,
+ input_count: 1,
+ is_segwit: false,
+ creation_sequence: Some(0), // Oldest UTXO
+ },
+ OutputGroup {
+ value: 1500,
+ weight: 150,
+ input_count: 1,
+ is_segwit: false,
+ creation_sequence: None, // No sequence
+ },
+ OutputGroup {
+ value: 2500,
+ weight: 250,
+ input_count: 1,
+ is_segwit: false,
+ creation_sequence: Some(5), // Newer UTXO
+ },
+ ];
+
+ let options = CoinSelectionOpt {
+ target_value: 4500,
+ target_feerate: 0.1,
+ long_term_feerate: None,
+ min_absolute_fee: 10,
+ base_weight: 100,
+ drain_weight: 50,
+ drain_cost: 0,
+ cost_per_input: 10,
+ cost_per_output: 5,
+ min_drain_value: 0,
+ excess_strategy: ExcessStrategy::ToFee,
+ };
+
+ let result = select_coin_fifo(&inputs, options);
+
+ assert!(result.is_ok());
+
+ let selection_output = result.unwrap();
+ // It should prioritize the ones with sequences: (3000, 1000, 2500) and then fall back on inputs without sequences
+ assert_eq!(selection_output.selected_inputs.len(), 3); // Should select 3 inputs
+ assert_eq!(selection_output.selected_inputs, vec![2, 0, 4]); // These are inputs with sequences
+
+ assert!(selection_output.waste.0 < 10000); // Check waste does not exceed an arbitrary limit.
+ }
+
  #[test]
  fn test_lowestlarger_successful() {
  let mut inputs = setup_lowestlarger_output_groups();