sdk/go: Add unmarshal for vaa.Address (#2076)

* sdk/go: Add unmarshal for vaa.Address

Change-Id: I1beb99f82673d1fc3225a8c6628a0019648d7e01

* sdk/go: review rework

Change-Id: I7c9179e674c019f46eebff13a071f997f20572f3

sdk/vaa/structs.go

@@ -123,6 +123,17 @@ func (a Address) MarshalJSON() ([]byte, error) {
 	return []byte(fmt.Sprintf(`"%s"`, a)), nil
 }
 
+// Standard marshal stores the Address like this: "[0,0,0,0,0,0,0,0,0,0,0,0,2,144,251,22,114,8,175,69,91,177,55,120,1,99,183,183,169,161,12,22]"
+// The above MarshalJSON stores it like this (66 bytes): ""0000000000000000000000000290fb167208af455bb137780163b7b7a9a10c16""
+func (a *Address) UnmarshalJSON(data []byte) error {
+	addr, err := StringToAddress(strings.Trim(string(data), `"`))
+	if err != nil {
+		return err
+	}
+	*a = addr
+	return nil
+}
+
 func (a Address) String() string {
 	return hex.EncodeToString(a[:])
 }

sdk/vaa/structs_test.go

@@ -5,6 +5,7 @@ import (
 	"crypto/elliptic"
 	"crypto/rand"
 	"encoding/hex"
+	"encoding/json"
 	"math/big"
 	"reflect"
 	"testing"
@@ -108,6 +109,59 @@ func TestAddress_MarshalJSON(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestAddress_UnmarshalJSON(t *testing.T) {
+	addr, _ := StringToAddress("0x0290fb167208af455bb137780163b7b7a9a10c16")
+
+	b, err := addr.MarshalJSON()
+	require.NoError(t, err)
+
+	var unmarshalAddr Address
+	err = unmarshalAddr.UnmarshalJSON(b)
+	require.NoError(t, err)
+
+	assert.Equal(t, addr, unmarshalAddr)
+}
+
+func TestAddress_Unmarshal(t *testing.T) {
+	addr, _ := StringToAddress("0x0290fb167208af455bb137780163b7b7a9a10c16")
+
+	b, err := json.Marshal(addr)
+	require.NoError(t, err)
+
+	var unmarshalAddr Address
+	err = json.Unmarshal(b, &unmarshalAddr)
+	require.NoError(t, err)
+
+	assert.Equal(t, addr, unmarshalAddr)
+}
+
+func TestAddress_UnmarshalEmptyBuffer(t *testing.T) {
+	b := []byte{}
+
+	var unmarshalAddr Address
+	err := json.Unmarshal(b, &unmarshalAddr)
+	require.Error(t, err)
+}
+
+func TestAddress_UnmarshalBufferTooShort(t *testing.T) {
+	addr, _ := StringToAddress("0x0290fb167208af455bb137780163b7b7a9a10c16")
+
+	b, err := json.Marshal(addr)
+	require.NoError(t, err)
+
+	var unmarshalAddr Address
+
+	// Lop off the first byte, and it should fail.
+	b1 := b[1:]
+	err = json.Unmarshal(b1, &unmarshalAddr)
+	assert.Error(t, err)
+
+	// Lop off the last byte, and it should fail.
+	b2 := b[0 : len(b)-1]
+	err = json.Unmarshal(b2, &unmarshalAddr)
+	assert.Error(t, err)
+}
+
 func TestAddress_String(t *testing.T) {
 	addr := Address{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4}
 	expected := "0000000000000000000000000000000000000000000000000000000000000004"