private List<MockId> setupIndexForTest() throws Exception {
    MockId blobId01 = new MockId("id01");
    MockId blobId02 = new MockId("id02");
    MockId blobId03 = new MockId("id03");
    MockId blobId04 = new MockId("id04");
    MockId blobId05 = new MockId("id05");
    MockId blobId06 = new MockId("id06");
    MockId blobId07 = new MockId("id07");
    MockId blobId08 = new MockId("id08");
    MockId blobId09 = new MockId("id09");
    MockId blobId10 = new MockId("id10");
    List<MockId> keys = new ArrayList<>();
    keys.add(blobId01);
    keys.add(blobId02);
    keys.add(blobId03);
    keys.add(blobId04);
    keys.add(blobId05);
    keys.add(blobId06);
    keys.add(blobId07);
    keys.add(blobId08);
    keys.add(blobId09);
    keys.add(blobId10);

    // indexes: [1 2] [3 4] [3d 5] [6 7] [2d 6d] [8 9] [1d 10] [1u 3u] [8d 10d]
    // journal:                                                  [3u 1u 10d 8d]

    helper.add(blobId01);
    helper.add(blobId02);
    helper.add(blobId03);
    helper.add(blobId04);

    helper.delete(blobId03);
    helper.add(blobId05);

    helper.add(blobId06);
    helper.add(blobId07);

    helper.delete(blobId02);
    helper.delete(blobId06);

    helper.add(blobId08);
    helper.add(blobId09);

    helper.delete(blobId01);
    helper.add(blobId10);

    helper.undelete(blobId03);
    helper.undelete(blobId01);

    helper.delete(blobId10);
    helper.delete(blobId08);
    // Let enough time to pass so that the above records become eligible for hard deletes.
    time.sleep(TimeUnit.DAYS.toMillis(2));
    return keys;
  }
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