Fix TransactionBuilder failing to debug P2PKH-only transactions

Author: mainnet-pat

packages/cashscript/src/TransactionBuilder.ts

@@ -17,6 +17,7 @@ import {
   isUnlockableUtxo,
   isStandardUnlockableUtxo,
   StandardUnlockableUtxo,
+  isP2PKHUnlocker,
 } from './interfaces.js';
 import { NetworkProvider } from './network/index.js';
 import {
@@ -161,6 +162,11 @@ export class TransactionBuilder {
   }
 
   debug(): DebugResults {
+    // do not debug a pure P2PKH-spend transaction
+    if (this.inputs.every((input) => isP2PKHUnlocker(input.unlocker))) {
+      return {};
+    }
+
     if (this.inputs.some((input) => !isStandardUnlockableUtxo(input))) {
       throw new Error('Cannot debug a transaction with custom unlocker');
     }

packages/cashscript/test/TransactionBuilder.test.ts

@@ -9,6 +9,8 @@ import {
   carolAddress,
   carolPriv,
   bobTokenAddress,
+  aliceAddress,
+  alicePriv,
 } from './fixture/vars.js';
 import { Network } from '../src/interfaces.js';
 import { utxoComparator, calculateDust, randomUtxo, randomToken, isNonTokenUtxo, isFungibleTokenUtxo } from '../src/utils.js';
@@ -263,4 +265,19 @@ describe('Transaction Builder', () => {
         .build();
     }).toThrow('Input is undefined');
   });
+
+  it('should not fail when spending from only P2PKH inputs', async () => {
+    const aliceUtxos = (await provider.getUtxos(aliceAddress)).filter(isNonTokenUtxo);
+    const sigTemplate = new SignatureTemplate(alicePriv);
+
+    expect(aliceUtxos.length).toBeGreaterThan(2);
+
+    const change = aliceUtxos[0].satoshis + aliceUtxos[1].satoshis - 1000n;
+
+    await expect(new TransactionBuilder({ provider })
+      .addInput(aliceUtxos[0], sigTemplate.unlockP2PKH())
+      .addInput(aliceUtxos[1], sigTemplate.unlockP2PKH())
+      .addOutput({ to: aliceAddress, amount: change })
+      .send()).resolves.not.toThrow();
+  });
 });