How to run test file？

[NobodyWHU]

When I want to run test file in knn or svd directory，there is always problem like this:

from ...knn.item_strategies import AllPossibleItemsStrategy, ItemsNeighborhoodStrategy
ValueError: Attempted relative import in non-package

I have already google it,but it still puzzles me .
So I want to get help here.
Some blog links may be awesome !Thanks!