code: public void testDeleteTaskWithDeleteReason(){
    if (processEngineConfiguration.getHistoryLevel().isAtLeast(HistoryLevel.ACTIVITY)) {
      Task task=taskService.newTask();
      task.setName("test task");
      taskService.saveTask(task);
      assertNotNull(task.getId());
      taskService.deleteTask(task.getId(),"deleted for testing purposes");
      HistoricTaskInstance historicTaskInstance=historyService.createHistoricTaskInstanceQuery().taskId(task.getId()).singleResult();
      assertNotNull(historicTaskInstance);
      assertEquals("deleted for testing purposes",historicTaskInstance.getDeleteReason());
      taskService.deleteTask(task.getId(),true);
    }
  }
  