[#168] object: Implement binary/JSON encoders/decoders on Attribute

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

pkg/object/attribute.go

@@ -43,3 +43,35 @@ func (a *Attribute) SetValue(v string) {
 func (a *Attribute) ToV2() *object.Attribute {
 	return (*object.Attribute)(a)
 }
+
+// Marshal marshals Attribute into a protobuf binary form.
+//
+// Buffer is allocated when the argument is empty.
+// Otherwise, the first buffer is used.
+func (d *Attribute) Marshal(b ...[]byte) ([]byte, error) {
+	var buf []byte
+	if len(b) > 0 {
+		buf = b[0]
+	}
+
+	return (*object.Attribute)(d).
+		StableMarshal(buf)
+}
+
+// Unmarshal unmarshals protobuf binary representation of Attribute.
+func (d *Attribute) Unmarshal(data []byte) error {
+	return (*object.Attribute)(d).
+		Unmarshal(data)
+}
+
+// MarshalJSON encodes Attribute to protobuf JSON format.
+func (d *Attribute) MarshalJSON() ([]byte, error) {
+	return (*object.Attribute)(d).
+		MarshalJSON()
+}
+
+// UnmarshalJSON decodes Attribute from protobuf JSON format.
+func (d *Attribute) UnmarshalJSON(data []byte) error {
+	return (*object.Attribute)(d).
+		UnmarshalJSON(data)
+}

pkg/object/attribute_test.go

@@ -21,3 +21,29 @@ func TestAttribute(t *testing.T) {
 	require.Equal(t, key, aV2.GetKey())
 	require.Equal(t, val, aV2.GetValue())
 }
+
+func TestAttributeEncoding(t *testing.T) {
+	a := NewAttribute()
+	a.SetKey("key")
+	a.SetValue("value")
+
+	t.Run("binary", func(t *testing.T) {
+		data, err := a.Marshal()
+		require.NoError(t, err)
+
+		a2 := NewAttribute()
+		require.NoError(t, a2.Unmarshal(data))
+
+		require.Equal(t, a, a2)
+	})
+
+	t.Run("json", func(t *testing.T) {
+		data, err := a.MarshalJSON()
+		require.NoError(t, err)
+
+		a2 := NewAttribute()
+		require.NoError(t, a2.UnmarshalJSON(data))
+
+		require.Equal(t, a, a2)
+	})
+}