[#209] object: Support splitID search attribute

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/object/splitid_test.go

@@ -0,0 +1,38 @@
+package object_test
+
+import (
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSplitID(t *testing.T) {
+	id := object.NewSplitID()
+
+	t.Run("toV2/fromV2", func(t *testing.T) {
+		data := id.ToV2()
+
+		newID := object.NewSplitIDFromV2(data)
+		require.NotNil(t, newID)
+
+		require.Equal(t, id, newID)
+	})
+
+	t.Run("string/parse", func(t *testing.T) {
+		idStr := id.String()
+
+		newID := object.NewSplitID()
+		require.NoError(t, newID.Parse(idStr))
+
+		require.Equal(t, id, newID)
+	})
+
+	t.Run("set UUID", func(t *testing.T) {
+		newUUID := uuid.New()
+		id.SetUUID(newUUID)
+
+		require.Equal(t, newUUID.String(), id.String())
+	})
+}