code: @Test public void openCloseTest() throws FileAlreadyExistException, InvalidPathException, TException, IOException {
    MasterClient masterClient=new MasterClient(mMasterInfo.getMasterAddress());
    Assert.assertFalse(masterClient.isConnected());
    masterClient.connect();
    Assert.assertTrue(masterClient.isConnected());
    masterClient.user_createFile("/file",Constants.DEFAULT_BLOCK_SIZE_BYTE);
    Assert.assertTrue(masterClient.user_getFileId("/file") != -1);
    masterClient.cleanConnect();
    Assert.assertFalse(masterClient.isConnected());
    masterClient.connect();
    Assert.assertTrue(masterClient.isConnected());
    Assert.assertTrue(masterClient.user_getFileId("/file") != -1);
  }
  