@Test
public void testToHexString() throws Exception {

  byte[] arr =
      new byte[] {
        (byte) 0x0,
        (byte) 0x1,
        (byte) 0x2,
        (byte) 0x3,
        (byte) 0x4,
        (byte) 0x55,
        (byte) 0x56,
        (byte) 0x57,
        (byte) 0x58,
        (byte) 0x59,
        (byte) 0xaa,
        (byte) 0xab,
        (byte) 0xac,
        (byte) 0xad,
        (byte) 0xae,
        (byte) 0xaf,
        (byte) 0xfa,
        (byte) 0xfb,
        (byte) 0xfc,
        (byte) 0xfd,
        (byte) 0xfe,
        (byte) 0xff
      };
  assertEquals(
      "00:01:02:03:04:55:56:57:58:59:aa:ab:ac:ad:ae:af:fa:fb:fc:fd:fe:ff",
      ByteArrays.toHexString(arr, ":"));
  assertEquals(
      "00 : 01 : 02 : 03 : 04 : 55 : 56 : 57 : 58 : 59 : aa : ab : ac : ad : ae : af : fa : fb : fc : fd : fe : ff",
      ByteArrays.toHexString(arr, " : "));
  assertEquals("55-56-57-58-59", ByteArrays.toHexString(arr, "-", 5, 5));
  assertEquals("aaabacadaeaf", ByteArrays.toHexString(arr, "", 10, 6));
}