@Test
  public void shouldNotRemoveAnyActivitiesWhenTaskHasNotActivities() {
    when(taskActivitiesDataService.byTask(TASK_ID)).thenReturn(new ArrayList<TaskActivity>());

    activityService.deleteActivitiesForTask(TASK_ID);

    verify(taskActivitiesDataService, never()).delete(any(TaskActivity.class));
  }
  @Test
  public void shouldDeleteAllTaskActivitiesForGivenTask() {
    when(taskActivitiesDataService.byTask(TASK_ID)).thenReturn(activities);

    activityService.deleteActivitiesForTask(TASK_ID);

    verify(taskActivitiesDataService, times(activities.size())).delete(any(TaskActivity.class));
  }
  @Test
  public void shouldReturnPaginatedActivitiesForGivenTask() {
    Set<TaskActivityType> types = new HashSet<>();
    types.addAll(Arrays.asList(TaskActivityType.values()));
    QueryParams queryParams = new QueryParams((Order) null);
    when(taskActivitiesDataService.byTaskAndActivityTypes(TASK_ID, types, queryParams))
        .thenReturn(activities);

    List<TaskActivity> actual = activityService.getTaskActivities(TASK_ID, types, queryParams);

    assertNotNull(actual);
    assertEquals(activities, actual);
  }