### Question:
OSUtils { public static List<String> getUserList() { try { if (isMacOS()) { return getUserListFromMac(); } else if (isWindows()) { return getUserListFromWindows(); } else { return getUserListFromLinux(); } } catch (Exception e) { logger.error(e.getMessage(), e); } return Collections.emptyList(); } private  OSUtils(); static double memoryUsage(); static double availablePhysicalMemorySize(); static double totalMemorySize(); static double loadAverage(); static double cpuUsage(); static List<String> getUserList(); static boolean createUser(String userName); static String getGroup(); static String exeCmd(String command); static String exeShell(String[] command); static int getProcessID(); static boolean isMacOS(); static boolean isWindows(); static String getOSName(); static Boolean checkResource(double systemCpuLoad, double systemReservedMemory); static Boolean checkResource(Configuration conf, Boolean isMaster); static final ThreadLocal<Logger> taskLoggerThreadLocal; static final String TWO_DECIMAL; static final double NEGATIVE_ONE; }### Answer:
@Test public void getUserList() { List<String> userList = OSUtils.getUserList(); Assert.assertNotEquals("System user list should not be empty", userList.size(), 0); logger.info("OS user list : {}", userList.toString()); }