fs use binary (um)marshaler

pkg/repo/fs/helper_test.go

@@ -2,6 +2,7 @@ package fs
 
 import (
 	"os"
+	"slices"
 	"testing"
 )
 
@@ -21,3 +22,16 @@ func createWorkDir(t *testing.T) (string, func()) {
 		}
 	}
 }
+
+type sampleData struct {
+	data []byte
+}
+
+func (sd *sampleData) UnmarshalBinary(data []byte) error {
+	sd.data = slices.Clone(data)
+	return nil
+}
+
+func (sd sampleData) MarshalBinary() (data []byte, err error) {
+	return sd.data, nil
+}