### Question:
ByteUtil { public static byte[] merge(byte[] ... byteArrays){ ByteArrayOutputStream outputStream = new ByteArrayOutputStream( ); try { for(byte[] a: byteArrays ){ outputStream.write( a ); } } catch (IOException e){ log.debug("Failed to merge"); } return outputStream.toByteArray( ); }  static byte[] merge(byte[] ... byteArrays); static ByteString merge(ByteString ... byteStrings);  }### Answer:
@Test public void testMerge_byteArrArr() { String random1 = RandomStringUtils.random(50, true, true); String random2 = RandomStringUtils.random(10, true, true); byte[] expResult = (random1+random2).getBytes(); byte[] result = ByteUtil.merge(random1.getBytes(), random2.getBytes()); Assertions.assertArrayEquals(expResult, result); }
@Test public void testMerge_identity() { String random1 = RandomStringUtils.random(50, true, true); byte[] expResult = (random1).getBytes(); byte[] result = ByteUtil.merge(random1.getBytes()); Assertions.assertArrayEquals(expResult, result); }
@Test public void testMerge_rightEmpty() { String random1 = RandomStringUtils.random(50, true, true); byte[] expResult = (random1).getBytes(); byte[] result = ByteUtil.merge(random1.getBytes(), new byte[0]); Assertions.assertArrayEquals(expResult, result); }
@Test public void testMerge_leftEmpty() { String random1 = RandomStringUtils.random(50, true, true); byte[] expResult = (random1).getBytes(); byte[] result = ByteUtil.merge(new byte[0], random1.getBytes()); Assertions.assertArrayEquals(expResult, result); }
@Test public void testMerge_ByteStringArr() { String random1 = RandomStringUtils.random(50, true, true); String random2 = RandomStringUtils.random(10, true, true); ByteString bRandom1 = ByteString.copyFrom(random1.getBytes()); ByteString bRandom2 = ByteString.copyFrom(random2.getBytes()); ByteString expResult = bRandom1.concat(bRandom2); ByteString result = ByteUtil.merge(bRandom1, bRandom2); assertEquals(expResult, result); }