names = append(names, f.Name)
		if _, err := f.Open(); err != nil {
			t.Errorf("Error opening %q: %v", f.Name, err)
		}
		if _, err := r.Open(f.Name); err == nil {
			t.Errorf("Opening %q with fs.FS API succeeded", f.Name)
		}
	}
	if !reflect.DeepEqual(names, entryNames) {
		t.Errorf("Unexpected file entries: %q", names)
	}
	if _, err := r.Open(""); err == nil {