transaction: unmarshal Output properly

Address is marshaled in base58 and needs to be
decoded accordingly.

pkg/core/transaction/output.go

@@ -24,6 +24,13 @@ type Output struct {
 	Position int `json:"n"`
 }
 
+type outputAux struct {
+	AssetID    util.Uint256 `json:"asset"`
+	Amount     util.Fixed8  `json:"value"`
+	ScriptHash string       `json:"address"`
+	Position   int          `json:"n"`
+}
+
 // NewOutput returns a new transaction output.
 func NewOutput(assetID util.Uint256, amount util.Fixed8, scriptHash util.Uint160) *Output {
 	return &Output{
@@ -56,3 +63,20 @@ func (out *Output) MarshalJSON() ([]byte, error) {
 		"n":       out.Position,
 	})
 }
+
+// UnmarshalJSON implements json.Unmarshaler interface.
+func (out *Output) UnmarshalJSON(data []byte) error {
+	var outAux outputAux
+	err := json.Unmarshal(data, &outAux)
+	if err != nil {
+		return err
+	}
+	out.ScriptHash, err = address.StringToUint160(outAux.ScriptHash)
+	if err != nil {
+		return err
+	}
+	out.Amount = outAux.Amount
+	out.AssetID = outAux.AssetID
+	out.Position = outAux.Position
+	return nil
+}

pkg/core/transaction/transaction_test.go

@@ -2,6 +2,7 @@ package transaction
 
 import (
 	"encoding/hex"
+	"encoding/json"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
@@ -175,3 +176,19 @@ func TestEncodingTXWithNoData(t *testing.T) {
 	tx.EncodeBinary(buf.BinWriter)
 	require.Error(t, buf.Err)
 }
+
+func TestMarshalUnmarshalJSON(t *testing.T) {
+	tx := NewContractTX()
+	tx.Outputs = []Output{{
+		AssetID:    util.Uint256{1, 2, 3, 4},
+		Amount:     567,
+		ScriptHash: util.Uint160{7, 8, 9, 10},
+		Position:   13,
+	}}
+	data, err := json.Marshal(tx)
+	require.NoError(t, err)
+
+	txNew := new(Transaction)
+	require.NoError(t, json.Unmarshal(data, txNew))
+	require.Equal(t, tx, txNew)
+}