### Question:
FileUtils { public static String readableFileSize(File file) { return readableFileSize(file.length()); }  static Optional<String> getFileText(String fileName); static String readFileText(String fileName); static void writeFileText(String fileName, String content); static void writeFileText(String fileName, boolean append, String content); static String readableFileSize(File file); static String readableFileSize(long size); static boolean createNewFile(File file);  }### Answer:
@Test public void testReadableFileSizeLong() { assertTrue("1 KB".equals(FileUtils.readableFileSize(1024))); }