### Question:
AramUtils { public static byte buildHashRefDo(short dataOffset, short dataOffsetMax, byte[] buf, short ofs, RuleEntry entry) { if (ofs >= dataOffset && ofs < dataOffsetMax) { buf[(short) (ofs - dataOffset)] = (byte) 0xC1; } ofs++; if (ofs >= dataOffset && ofs < dataOffsetMax) { buf[(short) (ofs - dataOffset)] = entry.getHashLength(); } ofs++; entry.getHash(buf, ofs, dataOffset, dataOffsetMax); return (byte) (entry.getHashLength() + 2); }  static byte buildRefArDo(short dataOffset, short dataOffsetMax, byte[] buf, short ofs, RuleEntry entry); static byte buildRefDo(short dataOffset, short dataOffsetMax, byte[] buf, short ofs, RuleEntry entry); static byte buildArDo(short dataOffset, short dataOffsetMax, byte[] buf, short ofs, RuleEntry entry); static byte buildAidRefDo(short dataOffset, short dataOffsetMax, byte[] buf, short ofs, RuleEntry entry); static byte buildHashRefDo(short dataOffset, short dataOffsetMax, byte[] buf, short ofs, RuleEntry entry);  }### Answer:
@Test public void hashRefDoTest() throws CardException { byte[] data = new byte[AramConstTest.VALID_HASH_REF_DO.length]; assertEquals(AramConstTest.VALID_HASH_REF_DO.length, AramUtils.buildHashRefDo(DEFAULT_DATA_OFFSET, DEFAULT_DATA_OFFSET_MAX, data, (short) 0, entry)); assertArrayEquals(AramConstTest.VALID_HASH_REF_DO, data); }