[#140] sdk/object: Implement ID comparison method

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

pkg/object/id.go

@@ -1,6 +1,7 @@
 package object
 
 import (
+	"bytes"
 	"crypto/sha256"
 
 	"github.com/nspcc-dev/neofs-api-go/v2/refs"
@@ -26,6 +27,14 @@ func (id *ID) SetSHA256(v [sha256.Size]byte) {
 	(*refs.ObjectID)(id).SetValue(v[:])
 }
 
+// Equal returns true if identifiers are identical.
+func (id *ID) Equal(id2 *ID) bool {
+	return bytes.Equal(
+		(*ID)(id).ToV2().GetValue(),
+		(*ID)(id2).ToV2().GetValue(),
+	)
+}
+
 // ToV2 converts ID to v2 ObjectID message.
 func (id *ID) ToV2() *refs.ObjectID {
 	return (*refs.ObjectID)(id)

pkg/object/id_test.go

@@ -22,3 +22,19 @@ func TestIDV2(t *testing.T) {
 
 	require.Equal(t, checksum[:], idV2.GetValue())
 }
+
+func TestID_Equal(t *testing.T) {
+	cs := randSHA256Checksum(t)
+
+	id1 := NewID()
+	id1.SetSHA256(cs)
+
+	id2 := NewID()
+	id2.SetSHA256(cs)
+
+	id3 := NewID()
+	id3.SetSHA256(randSHA256Checksum(t))
+
+	require.True(t, id1.Equal(id2))
+	require.False(t, id1.Equal(id3))
+}