### Question:
FileUtils { public static String getDownloadFilename(String filename) { String fileName = String.format("%s/download/%s/%s", DATA_BASEDIR, DateUtils.getCurrentTime(YYYYMMDDHHMMSS), filename); File file = new File(fileName); if (!file.getParentFile().exists()) { file.getParentFile().mkdirs(); } return fileName; } private  FileUtils(); static String suffix(String filename); static String getDownloadFilename(String filename); static String getUploadFilename(String tenantCode, String filename); static String getProcessExecDir(int projectId, int processDefineId, int processInstanceId, int taskInstanceId); static String getProcessExecDir(int projectId, int processDefineId, int processInstanceId); static String getResourceViewSuffixs(); static void createWorkDirAndUserIfAbsent(String execLocalPath, String userName); static boolean writeContent2File(String content, String filePath); static void writeStringToFile(File file, String data, Charset encoding); static void writeStringToFile(File file, String data, String encoding); static void writeStringToFile(File file, String data, Charset encoding, boolean append); static void writeStringToFile(File file, String data, String encoding, boolean append); static void writeStringToFile(File file, String data); static void writeStringToFile(File file, String data, boolean append); static FileOutputStream openOutputStream(File file); static FileOutputStream openOutputStream(File file, boolean append); static void deleteDir(String dir); static void deleteFile(String filename); static File[] getAllDir(String parentDir); static String readFile2Str(InputStream inputStream); static final Logger logger; static final String DATA_BASEDIR; static final ThreadLocal<Logger> taskLoggerThreadLocal; }### Answer:
@Test public void testGetDownloadFilename() { PowerMockito.mockStatic(DateUtils.class); PowerMockito.when(DateUtils.getCurrentTime(YYYYMMDDHHMMSS)).thenReturn("20190101101059"); Assert.assertEquals("/tmp/dolphinscheduler/download/20190101101059/test", FileUtils.getDownloadFilename("test")); }