refactor(utxo-core): extract BIP322 test fixtures into utility file

Create a shared utility file for BIP322 test fixtures to improve
code maintainability and reduce duplication across test files.

Co-authored-by: llm-git <[email protected]>

BTC-2361

TICKET: BTC-2361

Author: davidkaplanbitgo

modules/utxo-core/test/bip322/bip322.utils.ts

@@ -0,0 +1,7 @@
+import { payments, ECPair } from '@bitgo/utxo-lib';
+
+export const BIP322_WIF_FIXTURE = 'L3VFeEujGtevx9w18HD1fhRbCH67Az2dpCymeRE1SoPK6XQtaN2k';
+export const BIP322_PRV_FIXTURE = ECPair.fromWIF(BIP322_WIF_FIXTURE);
+export const BIP322_PAYMENT_P2WPKH_FIXTURE = payments.p2wpkh({
+  address: 'bc1q9vza2e8x573nczrlzms0wvx3gsqjx7vavgkx0l',
+});

modules/utxo-core/test/bip322/toSign.ts

@@ -1,17 +1,13 @@
 import assert from 'assert';
 
-import { payments, ECPair, Transaction } from '@bitgo/utxo-lib';
+import { Transaction } from '@bitgo/utxo-lib';
 
 import * as bip322 from '../../src/bip322';
 
+import { BIP322_PAYMENT_P2WPKH_FIXTURE, BIP322_PRV_FIXTURE as prv } from './bip322.utils';
 describe('BIP322 toSign', function () {
   describe('buildToSignPsbt', function () {
-    const WIF = 'L3VFeEujGtevx9w18HD1fhRbCH67Az2dpCymeRE1SoPK6XQtaN2k';
-    const prv = ECPair.fromWIF(WIF);
-    const scriptPubKey = payments.p2wpkh({
-      address: 'bc1q9vza2e8x573nczrlzms0wvx3gsqjx7vavgkx0l',
-    }).output as Buffer;
-
+    const scriptPubKey = BIP322_PAYMENT_P2WPKH_FIXTURE.output as Buffer;
     // Source: https://github.com/bitcoin/bips/blob/master/bip-0322.mediawiki#transaction-hashes
     const fixtures = [
       {

modules/utxo-core/test/bip322/toSpend.ts

@@ -1,9 +1,9 @@
 import assert from 'assert';
 
-import { payments } from '@bitgo/utxo-lib';
-
 import { buildToSpendTransaction, hashMessageWithTag } from '../../src/bip322';
 
+import { BIP322_PAYMENT_P2WPKH_FIXTURE } from './bip322.utils';
+
 describe('to_spend', function () {
   describe('Message hashing', function () {
     // Test vectors from BIP322
@@ -31,9 +31,7 @@ describe('to_spend', function () {
   });
 
   describe('build to_spend transaction', function () {
-    const scriptPubKey = payments.p2wpkh({
-      address: 'bc1q9vza2e8x573nczrlzms0wvx3gsqjx7vavgkx0l',
-    }).output as Buffer;
+    const scriptPubKey = BIP322_PAYMENT_P2WPKH_FIXTURE.output as Buffer;
 
     // Source: https://github.com/bitcoin/bips/blob/master/bip-0322.mediawiki#transaction-hashes
     const fixtures = [