[#168] session: Implement binary/JSON encoders/decoders on XHeader

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

v2/session/json.go

@@ -84,3 +84,23 @@ func (t *SessionToken) UnmarshalJSON(data []byte) error {
 
 	return nil
 }
+
+func (x *XHeader) MarshalJSON() ([]byte, error) {
+	return protojson.MarshalOptions{
+		EmitUnpopulated: true,
+	}.Marshal(
+		XHeaderToGRPCMessage(x),
+	)
+}
+
+func (x *XHeader) UnmarshalJSON(data []byte) error {
+	msg := new(session.XHeader)
+
+	if err := protojson.Unmarshal(data, msg); err != nil {
+		return err
+	}
+
+	*x = *XHeaderFromGRPCMessage(msg)
+
+	return nil
+}

v2/session/json_test.go

@@ -54,3 +54,15 @@ func TestSessionTokenJSON(t *testing.T) {
 
 	require.Equal(t, tok, tok2)
 }
+
+func TestXHeaderJSON(t *testing.T) {
+	x := generateXHeader("key", "value")
+
+	data, err := x.MarshalJSON()
+	require.NoError(t, err)
+
+	x2 := new(session.XHeader)
+	require.NoError(t, x2.UnmarshalJSON(data))
+
+	require.Equal(t, x, x2)
+}

v2/session/marshal.go

@@ -177,6 +177,17 @@ func (x *XHeader) StableSize() (size int) {
 	return size
 }
 
+func (x *XHeader) Unmarshal(data []byte) error {
+	m := new(session.XHeader)
+	if err := goproto.Unmarshal(data, m); err != nil {
+		return err
+	}
+
+	*x = *XHeaderFromGRPCMessage(m)
+
+	return nil
+}
+
 func (l *TokenLifetime) StableMarshal(buf []byte) ([]byte, error) {
 	if l == nil {
 		return []byte{}, nil

v2/session/marshal_test.go

@@ -46,16 +46,14 @@ func TestCreateResponseBody_StableMarshal(t *testing.T) {
 
 func TestXHeader_StableMarshal(t *testing.T) {
 	xheaderFrom := generateXHeader("X-Header-Key", "X-Header-Value")
-	transport := new(grpc.XHeader)
 
 	t.Run("non empty", func(t *testing.T) {
 		wire, err := xheaderFrom.StableMarshal(nil)
 		require.NoError(t, err)
 
-		err = goproto.Unmarshal(wire, transport)
-		require.NoError(t, err)
+		xheaderTo := new(session.XHeader)
+		require.NoError(t, xheaderTo.Unmarshal(wire))
 
-		xheaderTo := session.XHeaderFromGRPCMessage(transport)
 		require.Equal(t, xheaderFrom, xheaderTo)
 	})
 }