### Question:
Util { public static byte[] prependZeros(int n, byte[] message) { byte[] result = new byte[n + message.length]; Arrays.fill(result, (byte) 0); System.arraycopy(message, 0, result, n, message.length); return result; }  static byte[] prependZeros(int n, byte[] message); static byte[] removeZeros(int n, byte[] message); static void checkLength(byte[] data, int size); static byte[] zeros(int n); static boolean isValid(int status, String message); static byte[] slice(byte[] buffer, int start, int end); static byte[] merge(byte[] signature, byte[] message);  }### Answer:
@Test public void testPrependZeros() throws Exception { byte[] src = {'t', 'e', 's', 't'}; byte[] result = Util.prependZeros(3, src); Assert.assertArrayEquals(new byte[]{0, 0, 0, 't', 'e', 's', 't'}, result); }