[#41] chain: Fix ID serialization

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

pkg/chain/chain.go

@@ -31,6 +31,19 @@ type Chain struct {
 	MatchType MatchType
 }
 
+func (id ID) MarshalJSON() ([]byte, error) {
+	return json.Marshal([]byte(id))
+}
+
+func (id *ID) UnmarshalJSON(data []byte) error {
+	var idRaw []byte
+	if err := json.Unmarshal(data, &idRaw); err != nil {
+		return err
+	}
+	*id = ID(idRaw)
+	return nil
+}
+
 func (c *Chain) Bytes() []byte {
 	data, err := json.Marshal(c)
 	if err != nil {

pkg/chain/chain_test.go

@@ -9,6 +9,19 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestChainIDSerialization(t *testing.T) {
+	chainIDBytes := []byte{93, 236, 80, 138, 168, 3, 144, 92, 173, 141, 16, 42, 249, 90, 97, 109, 211, 169, 54, 163}
+
+	chain1 := &Chain{ID: ID(chainIDBytes)}
+	data := chain1.Bytes()
+
+	var chain2 Chain
+	err := chain2.DecodeBytes(data)
+	require.NoError(t, err)
+
+	require.Equal(t, chain1.ID, chain2.ID)
+}
+
 func TestEncodeDecode(t *testing.T) {
 	expected := Chain{
 		MatchType: MatchTypeFirstMatch,