@Test
  public void noReplicaStateTtlUpdateTest() {
    assumeTrue(operationTrackerType.equals(SIMPLE_OP_TRACKER));
    List<Port> portList = Collections.singletonList(new Port(PORT, PortType.PLAINTEXT));
    List<String> mountPaths = Collections.singletonList("mockMountPath");
    // set up one node per data center for testing
    MockDataNodeId origintingDcNode = new MockDataNodeId(portList, mountPaths, "dc-0");
    MockDataNodeId remoteDcNode = new MockDataNodeId(portList, mountPaths, "dc-1");
    datanodes = new ArrayList<>(Arrays.asList(origintingDcNode, remoteDcNode));
    mockPartition = new MockPartitionId();
    localDcName = datanodes.get(0).getDatacenterName();
    originatingDcName = localDcName;
    mockClusterMap = new MockClusterMap(false, datanodes, 1, Collections.singletonList(mockPartition), localDcName);
    // One replica down, one with no-state, one is ok
    populateReplicaList(3, ReplicaState.STANDBY, Collections.singletonList(origintingDcNode));
    populateReplicaList(2, ReplicaState.OFFLINE, Collections.singletonList(origintingDcNode));
    populateReplicaList(1, null, Collections.singletonList(origintingDcNode));

    // test both delete and Ttl Update cases
    for (RouterOperation operation : EnumSet.of(RouterOperation.DeleteOperation, RouterOperation.TtlUpdateOperation)) {
      repetitionTracker.clear();
      OperationTracker ot = getOperationTrackerForGetOrPut(true, 1, 2, operation, true);
      // issue delete/ttlUpdate requests to 2 local replica and 1 remote replica
      sendRequests(ot, 3, false);

      for (int i = 0; i < 2; ++i) {
        ot.onResponse(inflightReplicas.poll(), TrackedRequestFinalState.NOT_FOUND);
      }
      // for replicaState enabled operation tracker, only 1 eligible replica left, so numRequestsExpected = 1
      sendRequests(ot, replicasStateEnabled ? 0 : 2, false);
      // make 1 requests fail and 1 request succeed then replicaState enabled operation tracker should fail
      ot.onResponse(inflightReplicas.poll(), TrackedRequestFinalState.FAILURE);
      ot.onResponse(inflightReplicas.poll(), TrackedRequestFinalState.SUCCESS);
      if (replicasStateEnabled) {
        assertFalse("Operation should fail", ot.hasSucceeded());
      } else {
        // if replicasStateEnabled = false, operation tracker is able to succeed after 1 more request succeed
        ot.onResponse(inflightReplicas.poll(), TrackedRequestFinalState.SUCCESS);
        assertTrue("Operation should succeed", ot.hasSucceeded());
      }
      assertTrue("Operation should be done", ot.isDone());
    }
  }
Duplicate the GCN issue:
Among the 9 replicas, some are ERROR(in the GCN case, these are not listed in the Helix external view.
All the eligible replica returns either DiskDown or NotFound.
Originating Colo has 2 replica in the eligible replica, so we return NOT_FOUND.
ambry-router/src/test/java/com/github/ambry/router/OperationTrackerTest.java