rpc: implement verifyproof RPC

Test getproof and verifyproof together.

pkg/rpc/response/result/mpt.go

@@ -1,8 +1,10 @@
 package result
 
 import (
+	"bytes"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 
 	"github.com/nspcc-dev/neo-go/pkg/io"
 )
@@ -25,6 +27,12 @@ type GetProof struct {
 	Success bool         `json:"success"`
 }
 
+// VerifyProof is a result of verifyproof RPC.
+// nil Value is considered invalid.
+type VerifyProof struct {
+	Value []byte
+}
+
 // MarshalJSON implements json.Marshaler.
 func (p *ProofWithKey) MarshalJSON() ([]byte, error) {
 	w := io.NewBufBinWriter()
@@ -79,3 +87,36 @@ func (p *ProofWithKey) FromString(s string) error {
 	p.DecodeBinary(r)
 	return r.Err
 }
+
+// MarshalJSON implements json.Marshaler.
+func (p *VerifyProof) MarshalJSON() ([]byte, error) {
+	if p.Value == nil {
+		return []byte(`"invalid"`), nil
+	}
+	return []byte(`{"value":"` + hex.EncodeToString(p.Value) + `"}`), nil
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (p *VerifyProof) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, []byte(`"invalid"`)) {
+		p.Value = nil
+		return nil
+	}
+	var m map[string]string
+	if err := json.Unmarshal(data, &m); err != nil {
+		return err
+	}
+	if len(m) != 1 {
+		return errors.New("must have single key")
+	}
+	v, ok := m["value"]
+	if !ok {
+		return errors.New("invalid json")
+	}
+	b, err := hex.DecodeString(v)
+	if err != nil {
+		return err
+	}
+	p.Value = b
+	return nil
+}

pkg/rpc/response/result/mpt_test.go

@@ -55,3 +55,14 @@ func TestProofWithKey_EncodeString(t *testing.T) {
 	require.NoError(t, actual.FromString(expected.String()))
 	require.Equal(t, expected, &actual)
 }
+
+func TestVerifyProof_MarshalJSON(t *testing.T) {
+	t.Run("Good", func(t *testing.T) {
+		vp := &VerifyProof{random.Bytes(100)}
+		testserdes.MarshalUnmarshalJSON(t, vp, new(VerifyProof))
+	})
+	t.Run("NoValue", func(t *testing.T) {
+		vp := new(VerifyProof)
+		testserdes.MarshalUnmarshalJSON(t, vp, &VerifyProof{[]byte{1, 2, 3}})
+	})
+}