private void checkRecordHardDeleted(List<MockId> allKeys, Set<StoreKey> deletedKeys)
      throws IOException, StoreException {
    byte[] zeros = new byte[100];
    Arrays.fill(zeros, (byte) 0);
    for (StoreKey key : allKeys) {
      ByteBuffer recordContent = helper.readRecord(key);
      byte[] obtained = new byte[100];
      recordContent.position(100);
      recordContent.get(obtained, 0, 100);
      if (deletedKeys.contains(key)) {
        assertArrayEquals("HardDeleted Put Record should be zeroed out", obtained, zeros);
      } else {
        assertFalse("HardDeleted Put Record should not be zeroed out", Arrays.equals(zeros, obtained));
      }
    }
  }
Set up index for the test. This method would add some blobs, then deletes and undeletes some of them.
@return List of keys added to the index.
@throws Exception
ambry-store/src/test/java/com/github/ambry/store/HardDeleterTest.java