@Test(expected = QuorumException.class)
 public void testPutAllOperationThrowsExceptionWhenQuorumSizeNotMet() {
   HashMap<Integer, String> hashMap = new HashMap<Integer, String>();
   hashMap.put(123, "");
   cache4.putAll(hashMap);
 }
 @Test
 public void testPutAllOperationSuccessfulWhenQuorumSizeMet() {
   HashMap<Integer, String> hashMap = new HashMap<Integer, String>();
   hashMap.put(123, "");
   cache1.putAll(hashMap);
 }