txnbuild: add ClearSignatures functions to Transaction and FeeBumpTra…

…nsaction (#4173)

txnbuild/transaction.go

@@ -323,6 +323,12 @@ func (t *Transaction) SignHashX(preimage []byte) (*Transaction, error) {
 	return t.clone(extendedSignatures), nil
 }
 
+// ClearSignatures returns a new Transaction instance which extends the current instance
+// with signatures removed.
+func (t *Transaction) ClearSignatures() (*Transaction, error) {
+	return t.clone(nil), nil
+}
+
 // AddSignatureDecorated returns a new Transaction instance which extends the current instance
 // with an additional decorated signature(s).
 func (t *Transaction) AddSignatureDecorated(signature ...xdr.DecoratedSignature) (*Transaction, error) {
@@ -519,6 +525,12 @@ func (t *FeeBumpTransaction) SignHashX(preimage []byte) (*FeeBumpTransaction, er
 	return t.clone(extendedSignatures), nil
 }
 
+// ClearSignatures returns a new Transaction instance which extends the current instance
+// with signatures removed.
+func (t *FeeBumpTransaction) ClearSignatures() (*FeeBumpTransaction, error) {
+	return t.clone(nil), nil
+}
+
 // AddSignatureBase64 returns a new FeeBumpTransaction instance which extends the current instance
 // with an additional signature derived from the given base64-encoded signature.
 func (t *FeeBumpTransaction) AddSignatureBase64(network, publicKey, signature string) (*FeeBumpTransaction, error) {

txnbuild/transaction_test.go

@@ -3,13 +3,13 @@ package txnbuild
 import (
 	"crypto/sha256"
 	"encoding/base64"
-	"github.com/stellar/go/price"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/stellar/go/keypair"
 	"github.com/stellar/go/network"
+	"github.com/stellar/go/price"
 	"github.com/stellar/go/strkey"
 	"github.com/stellar/go/xdr"
 	"github.com/stretchr/testify/assert"
@@ -1692,6 +1692,83 @@ func TestAddSignatureBase64(t *testing.T) {
 	assert.Equal(t, expected, actual, "base64 xdr should match")
 }
 
+func TestTransaction_ClearSignatures(t *testing.T) {
+	kp0 := newKeypair0()
+	kp1 := newKeypair1()
+
+	tx, err := NewTransaction(
+		TransactionParams{
+			SourceAccount: &SimpleAccount{AccountID: kp0.Address(), Sequence: int64(9605939170639898)},
+			Operations: []Operation{&CreateAccount{
+				Destination:   "GCCOBXW2XQNUSL467IEILE6MMCNRR66SSVL4YQADUNYYNUVREF3FIV2Z",
+				Amount:        "10",
+				SourceAccount: kp1.Address(),
+			}},
+			BaseFee:    MinBaseFee,
+			Timebounds: NewInfiniteTimeout(),
+		},
+	)
+	require.NoError(t, err)
+	require.Len(t, tx.Signatures(), 0)
+
+	txWithSig, err := tx.Sign(network.TestNetworkPassphrase, kp0)
+	require.NoError(t, err)
+	require.Len(t, txWithSig.Signatures(), 1)
+
+	txSigCleared, err := txWithSig.ClearSignatures()
+	require.NoError(t, err)
+	require.Len(t, txSigCleared.Signatures(), 0)
+
+	expected, err := tx.Base64()
+	assert.NoError(t, err)
+	actual, err := txSigCleared.Base64()
+	assert.NoError(t, err)
+	assert.Equal(t, expected, actual)
+}
+
+func TestFeeBumpTransaction_ClearSignatures(t *testing.T) {
+	kp0 := newKeypair0()
+	kp1 := newKeypair1()
+
+	tx, err := NewTransaction(TransactionParams{
+		SourceAccount: &SimpleAccount{AccountID: kp0.Address(), Sequence: int64(9605939170639898)},
+		Operations: []Operation{&CreateAccount{
+			Destination:   "GCCOBXW2XQNUSL467IEILE6MMCNRR66SSVL4YQADUNYYNUVREF3FIV2Z",
+			Amount:        "10",
+			SourceAccount: kp1.Address(),
+		}},
+		BaseFee:    MinBaseFee,
+		Timebounds: NewInfiniteTimeout(),
+	})
+	require.NoError(t, err)
+	require.Len(t, tx.Signatures(), 0)
+	txWithSig, err := tx.Sign(network.TestNetworkPassphrase, kp0)
+	require.NoError(t, err)
+	require.Len(t, txWithSig.Signatures(), 1)
+
+	fbtx, err := NewFeeBumpTransaction(FeeBumpTransactionParams{
+		Inner:      txWithSig,
+		FeeAccount: kp0.Address(),
+		BaseFee:    MinBaseFee,
+	})
+	require.NoError(t, err)
+	require.Len(t, fbtx.Signatures(), 0)
+
+	fbtxWithSig, err := fbtx.Sign(network.TestNetworkPassphrase, kp0)
+	require.NoError(t, err)
+	require.Len(t, fbtxWithSig.Signatures(), 1)
+
+	fbtxSigCleared, err := fbtxWithSig.ClearSignatures()
+	require.NoError(t, err)
+	require.Len(t, fbtxSigCleared.Signatures(), 0)
+
+	expected, err := fbtx.Base64()
+	assert.NoError(t, err)
+	actual, err := fbtxSigCleared.Base64()
+	assert.NoError(t, err)
+	assert.Equal(t, expected, actual)
+}
+
 func TestReadChallengeTx_validSignedByServerAndClient(t *testing.T) {
 	serverKP := newKeypair0()
 	clientKP := newKeypair1()