Allowing signasgaspayer on unsigned tx (#1883)

* feat: allowing signing as gas payer on unsigned transactions

* feat: fixed unit tests

Author: GrandinLuc

packages/core/src/transaction/Transaction.ts

@@ -557,8 +557,8 @@ class Transaction {
     ): Transaction {
         if (Secp256k1.isValidPrivateKey(gasPayerPrivateKey)) {
             if (this.isDelegated) {
+                const senderHash = this.getTransactionHash(sender).bytes;
                 if (this.signature !== undefined) {
-                    const senderHash = this.getTransactionHash(sender).bytes;
                     return new Transaction(
                         this.body,
                         nc_utils.concatBytes(
@@ -567,12 +567,12 @@ class Transaction {
                             Secp256k1.sign(senderHash, gasPayerPrivateKey)
                         )
                     );
+                } else {
+                    return new Transaction(
+                        this.body,
+                        Secp256k1.sign(senderHash, gasPayerPrivateKey)
+                    );
                 }
-                throw new InvalidTransactionField(
-                    'Transaction.signAsGasPayer',
-                    'unsigned transaction: use signAsSender method',
-                    { fieldName: 'signature' }
-                );
             }
             throw new NotDelegatedTransaction(
                 'Transaction.signAsGasPayer',

packages/core/tests/transaction/Transaction.unit.test.ts

@@ -701,15 +701,17 @@ describe('Transaction class tests', () => {
             }).toThrowError(NotDelegatedTransaction);
         });
 
-        test('Throw <- unsigned tx', () => {
-            expect(() => {
-                Transaction.of(
-                    TransactionFixture.delegated.body
-                ).signAsGasPayer(
-                    Address.ofPrivateKey(SignerFix.privateKey),
-                    SignerFix.privateKey
-                );
-            }).toThrowError(InvalidTransactionField);
+        test('signature (only of the gasPayer) <- unsigned tx', () => {
+            expect(
+                (
+                    Transaction.of(
+                        TransactionFixture.delegated.body
+                    ).signAsGasPayer(
+                        Address.ofPrivateKey(SignerFix.privateKey),
+                        SignerFix.privateKey
+                    ).signature as Uint8Array
+                ).length
+            ).toBe(65);
         });
 
         test('Throw <- invalid private keys - delegated tx', () => {