private static File getSocketFile () throws IOException {
        String explicitFile = System.getProperty("org.newsclub.net.unix.testsocket");
        if ( explicitFile != null ) {
            return new File(explicitFile);
        }

        Path f = Files.createTempFile("junixsocket-test", ".sock");
        Files.delete(f);
        return f.toFile();
    }