t.Fatalf("MkdirAll(%q) failed; %v", path, err)
	}
	if err := os.RemoveAll(tmpDir); err != nil {
		t.Fatalf("RemoveAll(%q) failed; %v", tmpDir, err)
	}
}

func TestMkdirAllExtendedLength(t *testing.T) {
	t.Parallel()
	tmpDir := t.TempDir()

	const prefix = `\\?\`
	if len(tmpDir) < 4 || tmpDir[:4] != prefix {
		fullPath, err := syscall.FullPath(tmpDir)
		if err != nil {