fixup! fix: bitcoin input selector now tries to rescue dust if possible

Author: AngelCastilloB

packages/bitcoin/src/wallet/lib/input-selection/GreedyInputSelector.ts

@@ -3,6 +3,8 @@ import { UTxO } from '../providers';
 import { INPUT_SIZE, OUTPUT_SIZE, TRANSACTION_OVERHEAD, DUST_THRESHOLD } from '../common';
 import { InputSelector } from './InputSelector';
 
+const ZERO = BigInt(0);
+
 /**
  * A concrete implementation of InputSelector that uses a simple greedy algorithm.
  */
@@ -14,8 +16,8 @@ export class GreedyInputSelector implements InputSelector {
     feeRate: number
   ): { selectedUTxOs: UTxO[]; outputs: { address: string; value: number }[]; fee: number } | undefined {
     const selected: UTxO[] = [];
-    const totalOutput = outputs.reduce((acc, o) => acc + o.value, BigInt(0));
-    let inputSum = BigInt(0);
+    const totalOutput = outputs.reduce((acc, o) => acc + o.value, ZERO);
+    let inputSum = ZERO;
     let fee = 0;
 
     for (const utxo of utxos) {
@@ -29,7 +31,7 @@ export class GreedyInputSelector implements InputSelector {
 
     let change = inputSum - totalOutput - BigInt(fee);
 
-    if (change > BigInt(0) && Number(change) < DUST_THRESHOLD) {
+    if (change > ZERO && Number(change) < DUST_THRESHOLD) {
       const { change: newChange, fee: feeDelta } = this.attemptDustRescue({
         change,
         feeRate,
@@ -44,7 +46,7 @@ export class GreedyInputSelector implements InputSelector {
 
       if (change < BigInt(DUST_THRESHOLD)) {
         fee += Number(change);
-        change = BigInt(0);
+        change = ZERO;
       }
     }
 
@@ -64,7 +66,7 @@ export class GreedyInputSelector implements InputSelector {
   }
 
   /**
-   * Try to pull one more UtXO so that change exceeds the dust threshold if
+   * Try to pull one more UTxO so that change exceeds the dust threshold if
    * the value rescued is worth more than the added fee.
    */
   private attemptDustRescue({
@@ -84,7 +86,7 @@ export class GreedyInputSelector implements InputSelector {
     totalOutput: bigint;
     outputsCount: number;
   }): { change: bigint; fee: number } {
-    if (change === BigInt(0) || Number(change) >= DUST_THRESHOLD) return { change, fee: 0 };
+    if (change === ZERO || Number(change) >= DUST_THRESHOLD) return { change, fee: 0 };
 
     const originalChange = change;
     let feeDelta = 0;

packages/bitcoin/test/GreedyInputSelector.test.ts

@@ -7,16 +7,16 @@ describe('GreedyInputSelector', () => {
   const feeRate = 1; // sat/byte
   const changeAddress = 'change-address';
 
-  const createUtXO = (satoshis: bigint, id = Math.random().toString()) => ({
+  const createUTxO = (satoshis: bigint, id = Math.random().toString()) => ({
     txId: id,
     index: 0,
     address: 'address1',
     vout: 0,
     satoshis
   });
 
-  it('selects sufficient UtXOs and returns change', () => {
-    const utxos = [createUtXO(BigInt(5000)), createUtXO(BigInt(8000))];
+  it('selects sufficient UTxOs and returns change', () => {
+    const utxos = [createUTxO(BigInt(5000)), createUTxO(BigInt(8000))];
     const outputs = [{ address: 'address1', value: BigInt(4000) }];
     const result = selector.selectInputs(changeAddress, utxos, outputs, feeRate);
 
@@ -27,15 +27,15 @@ describe('GreedyInputSelector', () => {
   });
 
   it('returns undefined if inputs are insufficient', () => {
-    const utxos = [createUtXO(BigInt(1000))];
+    const utxos = [createUTxO(BigInt(1000))];
     const outputs = [{ address: 'address1', value: BigInt(2000) }];
     const result = selector.selectInputs(changeAddress, utxos, outputs, feeRate);
 
     expect(result).toBeUndefined();
   });
 
   it('includes all outputs and correct change when no dust', () => {
-    const utxos = [createUtXO(BigInt(10_000))];
+    const utxos = [createUTxO(BigInt(10_000))];
     const outputs = [
       { address: 'address1', value: BigInt(3000) },
       { address: 'address2', value: BigInt(2000) }
@@ -49,7 +49,7 @@ describe('GreedyInputSelector', () => {
   });
 
   it('adds dust change to fee instead of outputting it', () => {
-    const utxos = [createUtXO(BigInt(6000))];
+    const utxos = [createUTxO(BigInt(6000))];
     const outputs = [{ address: 'address1', value: BigInt(5500) }];
     const result = selector.selectInputs(changeAddress, utxos, outputs, feeRate);
 
@@ -60,8 +60,8 @@ describe('GreedyInputSelector', () => {
     expect(sumInputs - sumOutputs - result!.fee).toBe(0);
   });
 
-  it('rescues dust by including an extra UtXO when it is economical', () => {
-    const utxos = [createUtXO(BigInt(6000), 'utxo1'), createUtXO(BigInt(1000), 'utxo2')];
+  it('rescues dust by including an extra UTxO when it is economical', () => {
+    const utxos = [createUTxO(BigInt(6000), 'utxo1'), createUTxO(BigInt(1000), 'utxo2')];
     const outputs = [{ address: 'dest1', value: BigInt(5500) }];
 
     const result = selector.selectInputs(changeAddress, utxos, outputs, feeRate);
@@ -78,16 +78,16 @@ describe('GreedyInputSelector', () => {
 
   it('does NOT rescue dust when the extra input would cost more than the value rescued', () => {
     const bigFeeRate = 5;
-    // Single UtXO leaves ~290 sats dust (below dust threshold).
-    // Adding the second UtXO would cost ~340 sats in extra fee (68vB * 5) but
+    // Single UTxO leaves ~290 sats dust (below dust threshold).
+    // Adding the second UTxO would cost ~340 sats in extra fee (68vB * 5) but
     // only rescue ~260 sats, so it should NOT be added.
-    const utxos = [createUtXO(BigInt(9000), 'big_utxo'), createUtXO(BigInt(600), 'small_utxo')];
+    const utxos = [createUTxO(BigInt(9000), 'big_utxo'), createUTxO(BigInt(600), 'small_utxo')];
     const outputs = [{ address: 'dest1', value: BigInt(8000) }];
 
     const result = selector.selectInputs(changeAddress, utxos, outputs, bigFeeRate);
 
     expect(result).toBeDefined();
-    // Only the first (large) UtXO should be used.
+    // Only the first (large) UTxO should be used.
     expect(result!.selectedUTxOs.length).toBe(1);
     expect(result!.selectedUTxOs[0].txId).toBe('big_utxo');