@Test
  public void testAddRemoveAndGetPartitionsOnADisk(){
     Map<Integer, List<PartitionId>> diskToPartitionMap = new ConcurrentHashMap<>();

     prioritizationManager.start();
     int partitionCounter = 1;

     // Add 5 Replicas On Each Disk
     for(int diskId=1; diskId <= 10; diskId++){
       for(int numPartitions=0 ; numPartitions < 5; numPartitions++){
          PartitionId partition =
              new MockPartitionId(partitionCounter++, MockClusterMap.DEFAULT_PARTITION_CLASS,
                  clusterMap.getDataNodes(), diskId-1);
          diskToPartitionMap.putIfAbsent(diskId, new ArrayList<>());
          diskToPartitionMap.get(diskId).add(partition);
          assertTrue(prioritizationManager.addReplica(partition.getReplicaIds().get(0)));
       }
     }

     // Remove replicas and test number of replicas returned by getPartitionListForDisk.
     for(int diskId=1; diskId <= 10; diskId++){
       for(int numPartitions=0 ; numPartitions < 5; numPartitions++){
         PartitionId partition = diskToPartitionMap.get(diskId).get(numPartitions);
         assertTrue(prioritizationManager.removeReplica(partition.getReplicaIds().get(0).getDiskId(),
             partition.getReplicaIds().get(0)));
       }
     }
   }
Adding replicas to the prioritization manager before starting it should fail.
ambry-prioritization/src/test/java/com/github/ambry/replica/prioritization/FSFCPrioritizationManagerTest.java