### Question:
FieldFormatHelper { public static String formatFileLength(final long bytes) { return FileUtils.byteCountToDisplaySize(bytes); }  static String formatFileLength(final long bytes); static String formatByteProgress(final long totalBytes,
            final long currentBytes, final int padValue); static String formatFileProgress(final int totalFiles,
            final int currentFiles, final int padValue);  }### Answer:
@Test public void testFormatFileLength() { long testVal = 1; String actual = FieldFormatHelper.formatFileLength(testVal); TestCase.assertEquals("should be expressed in bytes", "1 bytes", actual); testVal = 2 * 1024 * 1024; actual = FieldFormatHelper.formatFileLength(testVal); TestCase.assertEquals("should be expressed in MB", "2 MB", actual); testVal = (long) 2 * 1024 * 1024 * 1024; actual = FieldFormatHelper.formatFileLength(testVal); TestCase.assertEquals("should be expressed in GB", "2 GB", actual); }