### Question:
Bytes { public static String toHexWithZeros(byte b) { if (b == 0) { return "00"; } String s = toHex(b); if (s.length() == 1) { return "0" + s; } else { return s; } }  static byte[] toByteArray(int... uints); static int toInt(byte[] pb, boolean bigEndian); static int normalize(int i, int bitCount); static void normalize(int iarr[], int bitCount); static byte[] toByteArray(int i, int size, boolean isBigEndian); static int toInt(byte b0, byte b1, byte b2, byte b3, boolean bigEndian); static byte[] toByteArray(int i, boolean bigEndian); static byte[] toByteArray(short i, boolean bigEndian); static int[] toIntArray(byte[] ba, int amount, boolean bigEndian); static int[] toIntArray(byte[] ba, final int amount, final int bytePerInteger,
      boolean bigEndian); static int[] toReducedBitIntArray(
      byte[] ba,
      final int amount,
      int bytePerInteger,
      int bitAmount,
      boolean bigEndian); static short[] toShortArray(byte[] ba, int amount, boolean bigEndian); static byte[] toByteArray(short[] sa, int amount, boolean bigEndian); static byte[] toByteArray(int[] ia, int amount, int bytePerInteger, boolean bigEndian); static String toHexWithZeros(byte b); static String toHex(byte b); static String toHex(byte[] bytes); static String toHexWithZeros(byte[] bytes); static void hexDump(OutputStream os, byte[] bytes, int columns); static void hexDump(byte[] bytes, int columns); static final byte[] EMPTY_BYTE_ARRAY; }### Answer:
@Test public void toHexWithZerostWithZerosTest() { assertEquals(toHexWithZeros((byte) 0), "00"); assertEquals(toHexWithZeros((byte) 1), "01"); assertEquals(toHexWithZeros((byte) 15), "0f"); assertEquals(toHexWithZeros((byte) 127), "7f"); assertEquals(toHexWithZeros((byte) 0xcc), "cc"); assertEquals(toHexWithZeros(new byte[]{(byte) 0x01}), "01"); assertEquals(toHexWithZeros(new byte[]{(byte) 0xcc}), "cc"); assertEquals(toHexWithZeros(new byte[]{0x00, 0x00}), "0000"); assertEquals(toHexWithZeros(new byte[]{0x01, 0x1f, (byte) 0xcc}), "011fcc"); assertEquals(toHexWithZeros(new byte[]{0x01, 0x1f, 0x00}), "011f00"); assertEquals(toHexWithZeros(new byte[]{0x00, 0x01, 0x1f, 0x01, 0x00, 0x00}), "00011f010000"); }
@Test(expected = NullPointerException.class) public void toHexWithZerosExceptionTest() { toHexWithZeros(null); }