Ensure packObjects test helper produces deterministic hashes by iterating in sorted order

Author: airhorns

internal/files/writer.go

@@ -90,7 +90,7 @@ func writeObject(rootDir string, cacheObjectsDir string, reader *db.TarReader, h
 			return err
 		}
 		hashHex := hex.EncodeToString(content)
-		return hardlinkDir(filepath.Join(cacheObjectsDir, hashHex, header.Name), path)
+		return HardlinkDir(filepath.Join(cacheObjectsDir, hashHex, header.Name), path)
 
 	case tar.TypeReg:
 		dir := filepath.Dir(path)
@@ -193,7 +193,7 @@ func makeSymlink(oldname, newname string) error {
 	return nil
 }
 
-func hardlinkDir(olddir, newdir string) error {
+func HardlinkDir(olddir, newdir string) error {
 	if fileExists(newdir) {
 		err := os.RemoveAll(newdir)
 		if err != nil {
@@ -203,7 +203,7 @@ func hardlinkDir(olddir, newdir string) error {
 
 	return filepath.Walk(olddir, func(oldpath string, info fs.FileInfo, err error) error {
 		if err != nil {
-			return err
+			return fmt.Errorf("failed to walk dir: %v, %w", info, err)
 		}
 
 		newpath := filepath.Join(newdir, strings.TrimPrefix(oldpath, olddir))

test/shared_test.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
 	"testing"
 
@@ -223,13 +224,22 @@ func packObjects(tc util.TestCtx, objects map[string]expectedObject) []byte {
 	contentWriter := db.NewTarWriter()
 	defer contentWriter.Close()
 
-	for path, info := range objects {
+	var keys []string
+	for key := range objects {
+		keys = append(keys, key)
+	}
+
+	sort.Strings(keys)
+
+	// iterate the objects for packing in a deterministic order
+	for _, key := range keys {
+		info := objects[key]
 		mode := info.mode
 		if mode == 0 {
 			mode = 0755
 		}
 
-		object := db.NewUncachedTarObject(path, mode, int64(len(info.content)), info.deleted, []byte(info.content))
+		object := db.NewUncachedTarObject(key, mode, int64(len(info.content)), info.deleted, []byte(info.content))
 
 		err := contentWriter.WriteObject(&object)
 		require.NoError(tc.T(), err, "write content to TAR")