neorpc: adjust the way SignerWithWitness is marshalled

Marshal account with `0x` prefix and add a test.

Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>

pkg/neorpc/types.go

@@ -97,7 +97,7 @@ func (s *SignerWithWitness) MarshalJSON() ([]byte, error) {
 		return nil, fmt.Errorf("failed to marshal scopes: %w", err)
 	}
 	signer := &signerWithWitnessAux{
-		Account:            s.Account.StringLE(),
+		Account:            `0x` + s.Account.StringLE(),
 		Scopes:             sc,
 		AllowedContracts:   s.AllowedContracts,
 		AllowedGroups:      s.AllowedGroups,

pkg/neorpc/types_test.go

@@ -0,0 +1,40 @@
+package neorpc
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/internal/testserdes"
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSignerWithWitnessMarshalUnmarshalJSON(t *testing.T) {
+	s := &SignerWithWitness{
+		Signer: transaction.Signer{
+			Account:          util.Uint160{1, 2, 3},
+			Scopes:           transaction.CalledByEntry | transaction.CustomContracts,
+			AllowedContracts: []util.Uint160{{1, 2, 3, 4}},
+		},
+		Witness: transaction.Witness{
+			InvocationScript:   []byte{1, 2, 3},
+			VerificationScript: []byte{4, 5, 6},
+		},
+	}
+	testserdes.MarshalUnmarshalJSON(t, s, &SignerWithWitness{})
+
+	// Check marshalling separately to ensure Scopes are marshalled OK.
+	expected := `{"account":"0xcadb3dc2faa3ef14a13b619c9a43124755aa2569","scopes":"CalledByEntry, CustomContracts"}`
+	acc, err := util.Uint160DecodeStringLE("cadb3dc2faa3ef14a13b619c9a43124755aa2569")
+	require.NoError(t, err)
+	s = &SignerWithWitness{
+		Signer: transaction.Signer{
+			Account: acc,
+			Scopes:  transaction.CalledByEntry | transaction.CustomContracts,
+		},
+	}
+	actual, err := json.Marshal(s)
+	require.NoError(t, err)
+	require.Equal(t, expected, string(actual))
+}