单元测试：警告在视图不在窗口层次结构中的视图上显示视图

I have a UIViewController with a UICollectionView of which is not the root my app but is reached via a segue. This UICollectionView has UICollectionViewCells having an imageView with a UITapGestureRecognizer that when triggered helps present a UIAlertViewController. I have been having troubles testing my show alert method as I get this warning : I have a UIViewController with a UICollectionVi