1 files changed, 28 insertions, 0 deletions
diff --git a/src/testing/fstest/mapfs_test.go b/src/testing/fstest/mapfs_test.go
index 2abedd6735..c8d29283b2 100644
--- a/src/testing/fstest/mapfs_test.go
+++ b/src/testing/fstest/mapfs_test.go
@@ -5,6 +5,9 @@
 package fstest
 
 import (
+	"fmt"
+	"io/fs"
+	"strings"
 	"testing"
 )
 
@@ -17,3 +20,28 @@ func TestMapFS(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestMapFSChmodDot(t *testing.T) {
+	m := MapFS{
+		"a/b.txt": &MapFile{Mode: 0666},
+		".":       &MapFile{Mode: 0777 | fs.ModeDir},
+	}
+	buf := new(strings.Builder)
+	fs.WalkDir(m, ".", func(path string, d fs.DirEntry, err error) error {
+		fi, err := d.Info()
+		if err != nil {
+			return err
+		}
+		fmt.Fprintf(buf, "%s: %v\n", path, fi.Mode())
+		return nil
+	})
+	want := `
+.: drwxrwxrwx
+a: d---------
+a/b.txt: -rw-rw-rw-
+`[1:]
+	got := buf.String()
+	if want != got {
+		t.Errorf("MapFS modes want:\n%s\ngot:\n%s\n", want, got)
+	}
+}