public static NamenodeRole convert(NamenodeRoleProto role) {
    switch (role) {
    case NAMENODE:
      return NamenodeRole.NAMENODE;
    case BACKUP:
      return NamenodeRole.BACKUP;
    case CHECKPOINT:
      return NamenodeRole.CHECKPOINT;
    }
    return null;
  }
@Test
  public void testConvertBlockRecoveryCommand() {
    DatanodeInfo di1 = DFSTestUtil.getLocalDatanodeInfo();
    DatanodeInfo di2 = DFSTestUtil.getLocalDatanodeInfo();
    DatanodeInfo[] dnInfo = new DatanodeInfo[] { di1, di2 };

    List<RecoveringBlock> blks = ImmutableList.of(
      new RecoveringBlock(getExtendedBlock(1), dnInfo, 3),
      new RecoveringBlock(getExtendedBlock(2), dnInfo, 3)
    );
    
    BlockRecoveryCommand cmd = new BlockRecoveryCommand(blks);
    BlockRecoveryCommandProto proto = PBHelper.convert(cmd);
    assertEquals(1, proto.getBlocks(0).getBlock().getB().getBlockId());
    assertEquals(2, proto.getBlocks(1).getBlock().getB().getBlockId());
    
    BlockRecoveryCommand cmd2 = PBHelper.convert(proto);
    
    List<RecoveringBlock> cmd2Blks = Lists.newArrayList(
        cmd2.getRecoveringBlocks());
    assertEquals(blks.get(0).getBlock(), cmd2Blks.get(0).getBlock());
    assertEquals(blks.get(1).getBlock(), cmd2Blks.get(1).getBlock());
    assertEquals(Joiner.on(",").join(blks), Joiner.on(",").join(cmd2Blks));
    assertEquals(cmd.toString(), cmd2.toString());
  }