return nil, err
	}

	if _, err := routeFile.Write([]byte(content)); err != nil {
		return routeFile, err
	}
	err = routeFile.Close()
	return routeFile, err
}

func TestFailGettingIPv4Routes(t *testing.T) {
	defer func() { v4File.name = ipv4RouteFile }()

	// Try failure to open file (should not occur, as caller ensures we have IPv4 route file, but being thorough)
	v4File.name = "no-such-file"