internal/testgit: LsTree

1 files changed, 47 insertions, 0 deletions

diff --git a/internal/testgit/tree.go b/internal/testgit/tree.go
index 77bea568..cf6ab1bf 100644
--- a/internal/testgit/tree.go
+++ b/internal/testgit/tree.go
@@ -40,3 +40,50 @@ func (repo *Repo) MkTree(tb testing.TB, entries []TreeEntry) (id.ObjectID, error
 
 	return treeID, nil
 }
+
+// LsTree lists the top-level entries of a tree object in Git tree order.
+func (repo *Repo) LsTree(tb testing.TB, oid id.ObjectID) ([]TreeEntry, error) {
+	tb.Helper()
+
+	stdout, err := repo.run(tb, nil, "git", "ls-tree", "-z", "--full-tree", "--end-of-options", oid.String())
+	if err != nil {
+		return nil, fmt.Errorf("ls-tree: %w", err)
+	}
+
+	var entries []TreeEntry
+
+	for _, record := range bytes.Split(stdout, []byte{0}) {
+		if len(record) == 0 {
+			continue
+		}
+
+		meta, name, found := bytes.Cut(record, []byte{'\t'})
+		if !found {
+			return nil, fmt.Errorf("ls-tree: record %q has no tab separator", record)
+		}
+
+		fields := bytes.SplitN(meta, []byte{' '}, 3)
+		if len(fields) != 3 {
+			return nil, fmt.Errorf("ls-tree: record %q has malformed metadata", record)
+		}
+
+		ty, err := typ.Parse(string(fields[1]))
+		if err != nil {
+			return nil, fmt.Errorf("ls-tree: record %q: parse type: %w", record, err)
+		}
+
+		entryOID, err := repo.objectFormat.FromString(string(fields[2]))
+		if err != nil {
+			return nil, fmt.Errorf("ls-tree: record %q: parse oid: %w", record, err)
+		}
+
+		entries = append(entries, TreeEntry{
+			Mode: string(fields[0]),
+			Type: ty,
+			OID:  entryOID,
+			Name: string(name),
+		})
+	}
+
+	return entries, nil
+}