fErr = rootCmd.Execute()

	switch fErr.(type) {
	case istioctlutil.CommandParseError:
		// do nothing
	default:
		t.Errorf("Expected a CommandParseError, but got %q.", fErr)
	}

	// all of the subcommands
	rootCmd = GetRootCmd([]string{"x", "authz", "check", "--unknown-flag"})
	fErr = rootCmd.Execute()

	switch fErr.(type) {
	case istioctlutil.CommandParseError:
		// do nothing
	default: