### Question:
Formats { public static String toFixLengthSizeUnit(Long size) { if (size == null) { return "NaN"; } if (size < KB_SIZE) { return String.format("%4d", size); } if (size < MB_SIZE) { return String.format("%4dk", size / KB_SIZE); } if (size < GB_SIZE) { return String.format("%4dm", size / MB_SIZE); } if (size < TB_SIZE) { return String.format("%4dg", size / GB_SIZE); } return String.format("%4dt", size / TB_SIZE); }  static void disableAnsi(); static void setCleanClearTerminal(); static void setTextClearTerminal(); static String toMBWithColor(long bytes, LongWarning warning); static String toColor(long value, LongWarning warning); static String red(String value); static String yellow(String value); static String toMB(long bytes); static String toSizeUnitWithColor(Long size, LongWarning warning); static String toSizeUnit(Long size); static String toFixLengthSizeUnit(Long size); static String toTimeUnit(long millis); static String formatUsage(Usage usage); static String formatUsageWithColor(Usage usage, LongWarning warning); static String[] colorAnsi(long value, LongWarning warning); static String[] colorAnsi(double value, DoubleWarning warning); static String rightStr(String str, int length); static String leftStr(String str, int length); static String shortName(String str, int length, int rightLength); static String join(List<String> list, String delim); static long parseFromSize(String str); static void clearTerminal(); static final long MB_SIZE; static boolean isWindows; }### Answer:
@Test public void toFixLengthSizeUnitInputNullOutputNotNull() { final Long size = null; final String retval = Formats.toFixLengthSizeUnit(size); Assert.assertEquals("NaN", retval); }
@Test public void toFixLengthSizeUnitInputPositiveOutputNotNull() { final Long size = 4_611_686_018_427_387_906L; final String retval = Formats.toFixLengthSizeUnit(size); Assert.assertEquals("4194304t", retval); }