keys: implement PublicKeys.Copy()

Implement convenient wrapper over explicit allocation and copying.

pkg/core/blockchain.go

@@ -1243,9 +1243,7 @@ func (bc *Blockchain) PoolTx(t *transaction.Transaction) error {
 
 //GetStandByValidators returns validators from the configuration.
 func (bc *Blockchain) GetStandByValidators() keys.PublicKeys {
-	res := make(keys.PublicKeys, len(bc.sbValidators))
-	copy(res, bc.sbValidators)
-	return res
+	return bc.sbValidators.Copy()
 }
 
 // GetValidators returns next block validators.

pkg/crypto/keys/publickey.go

@@ -55,6 +55,13 @@ func (keys PublicKeys) Contains(pKey *PublicKey) bool {
 	return false
 }
 
+// Copy returns copy of keys.
+func (keys PublicKeys) Copy() PublicKeys {
+	res := make(PublicKeys, len(keys))
+	copy(res, keys)
+	return res
+}
+
 // Unique returns set of public keys.
 func (keys PublicKeys) Unique() PublicKeys {
 	unique := PublicKeys{}

pkg/crypto/keys/publickey_test.go

@@ -37,6 +37,23 @@ func TestEncodeDecodePublicKey(t *testing.T) {
 	}
 }
 
+func TestPublicKeys_Copy(t *testing.T) {
+	pubs := make(PublicKeys, 5)
+	for i := range pubs {
+		priv, err := NewPrivateKey()
+		require.NoError(t, err)
+		pubs[i] = priv.PublicKey()
+	}
+
+	cp := pubs.Copy()
+	priv, err := NewPrivateKey()
+	require.NoError(t, err)
+	cp[0] = priv.PublicKey()
+
+	require.NotEqual(t, pubs[0], cp[0])
+	require.Equal(t, pubs[1:], cp[1:])
+}
+
 func TestNewPublicKeyFromBytes(t *testing.T) {
 	priv, err := NewPrivateKey()
 	require.NoError(t, err)

pkg/smartcontract/context/context_test.go

@@ -70,8 +70,7 @@ func TestParameterContext_AddSignatureMultisig(t *testing.T) {
 	tx := getContractTx()
 	c := NewParameterContext("Neo.Core.ContractTransaction", tx)
 	privs, pubs := getPrivateKeys(t, 4)
-	pubsCopy := make(keys.PublicKeys, len(pubs))
-	copy(pubsCopy, pubs)
+	pubsCopy := keys.PublicKeys(pubs).Copy()
 	script, err := smartcontract.CreateMultiSigRedeemScript(3, pubsCopy)
 	require.NoError(t, err)