rpcclient: add gas package for the GAS contract

Test it with the RPC server.

cli/wallet/nep17.go

@@ -17,6 +17,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/encoding/fixedn"
 	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient"
+	"github.com/nspcc-dev/neo-go/pkg/rpcclient/gas"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/invoker"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/nep17"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
@@ -241,7 +242,8 @@ func getNEP17Balance(ctx *cli.Context) error {
 				if err != nil {
 					// Try to get native NEP17 with matching symbol.
 					var gasSymbol, neoSymbol string
-					gasSymbol, h, err = getNativeNEP17Symbol(c, nativenames.Gas)
+					g := gas.NewReader(invoker.New(c, nil))
+					gasSymbol, err = g.Symbol()
 					if err != nil {
 						continue
 					}
@@ -253,6 +255,8 @@ func getNEP17Balance(ctx *cli.Context) error {
 						if neoSymbol != name {
 							continue
 						}
+					} else {
+						h = gas.Hash
 					}
 				}
 			}

pkg/rpcclient/gas/gas.go

@@ -0,0 +1,26 @@
+/*
+Package gas provides a convenience wrapper for GAS contract to use it via RPC.
+
+GAS itself only has standard NEP-17 methods, so this package only contains its
+hash and allows to create NEP-17 structures in an easier way.
+*/
+package gas
+
+import (
+	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
+	"github.com/nspcc-dev/neo-go/pkg/core/state"
+	"github.com/nspcc-dev/neo-go/pkg/rpcclient/nep17"
+)
+
+// Hash stores the hash of the native GAS contract.
+var Hash = state.CreateNativeContractHash(nativenames.Gas)
+
+// NewReader creates a NEP-17 reader for the GAS contract.
+func NewReader(invoker nep17.Invoker) *nep17.TokenReader {
+	return nep17.NewReader(invoker, Hash)
+}
+
+// New creates a NEP-17 contract instance for the native GAS contract.
+func New(actor nep17.Actor) *nep17.Token {
+	return nep17.New(actor, Hash)
+}

pkg/rpcclient/gas/gas_test.go

@@ -0,0 +1,40 @@
+package gas
+
+import (
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/stretchr/testify/require"
+)
+
+type testAct struct {
+	err error
+	res *result.Invoke
+	tx  *transaction.Transaction
+	txh util.Uint256
+	vub uint32
+}
+
+func (t *testAct) Call(contract util.Uint160, operation string, params ...interface{}) (*result.Invoke, error) {
+	return t.res, t.err
+}
+func (t *testAct) MakeRun(script []byte) (*transaction.Transaction, error) {
+	return t.tx, t.err
+}
+func (t *testAct) MakeUnsignedRun(script []byte, attrs []transaction.Attribute) (*transaction.Transaction, error) {
+	return t.tx, t.err
+}
+func (t *testAct) SendRun(script []byte) (util.Uint256, uint32, error) {
+	return t.txh, t.vub, t.err
+}
+
+func TestNew(t *testing.T) {
+	ta := &testAct{}
+	gr := NewReader(ta)
+	require.NotNil(t, gr)
+
+	g := New(ta)
+	require.NotNil(t, g)
+}

pkg/services/rpcsrv/client_test.go

@@ -20,7 +20,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/core"
 	"github.com/nspcc-dev/neo-go/pkg/core/fee"
-	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
 	"github.com/nspcc-dev/neo-go/pkg/core/native/noderoles"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
@@ -31,6 +30,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/network"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/actor"
+	"github.com/nspcc-dev/neo-go/pkg/rpcclient/gas"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/invoker"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/nep17"
 	"github.com/nspcc-dev/neo-go/pkg/rpcclient/nns"
@@ -781,14 +781,11 @@ func TestCreateNEP17TransferTx(t *testing.T) {
 	acc := wallet.NewAccountFromPrivateKey(priv)
 	addr := priv.PublicKey().GetScriptHash()
 
-	gasContractHash, err := c.GetNativeContractHash(nativenames.Gas)
-	require.NoError(t, err)
-
 	t.Run("default scope", func(t *testing.T) {
 		act, err := actor.NewSimple(c, acc)
 		require.NoError(t, err)
-		gas := nep17.New(act, gasContractHash)
+		gasprom := gas.New(act)
-		tx, err := gas.TransferUnsigned(addr, util.Uint160{}, big.NewInt(1000), nil)
+		tx, err := gasprom.TransferUnsigned(addr, util.Uint160{}, big.NewInt(1000), nil)
 		require.NoError(t, err)
 		require.NoError(t, acc.SignTx(testchain.Network(), tx))
 		require.NoError(t, chain.VerifyTx(tx))
@@ -805,8 +802,8 @@ func TestCreateNEP17TransferTx(t *testing.T) {
 			Account: acc,
 		}})
 		require.NoError(t, err)
-		gas := nep17.New(act, gasContractHash)
+		gasprom := gas.New(act)
-		_, err = gas.TransferUnsigned(addr, util.Uint160{}, big.NewInt(1000), nil)
+		_, err = gasprom.TransferUnsigned(addr, util.Uint160{}, big.NewInt(1000), nil)
 		require.Error(t, err)
 	})
 	t.Run("customcontracts scope", func(t *testing.T) {
@@ -814,13 +811,13 @@ func TestCreateNEP17TransferTx(t *testing.T) {
 			Signer: transaction.Signer{
 				Account:          priv.PublicKey().GetScriptHash(),
 				Scopes:           transaction.CustomContracts,
-				AllowedContracts: []util.Uint160{gasContractHash},
+				AllowedContracts: []util.Uint160{gas.Hash},
 			},
 			Account: acc,
 		}})
 		require.NoError(t, err)
-		gas := nep17.New(act, gasContractHash)
+		gasprom := gas.New(act)
-		tx, err := gas.TransferUnsigned(addr, util.Uint160{}, big.NewInt(1000), nil)
+		tx, err := gasprom.TransferUnsigned(addr, util.Uint160{}, big.NewInt(1000), nil)
 		require.NoError(t, err)
 		require.NoError(t, acc.SignTx(testchain.Network(), tx))
 		require.NoError(t, chain.VerifyTx(tx))