code: def test_fit(self):
      dataset = SequentialDataset.from_usit(self.data)
      model = NextItemRecommender("")
      model.fit(dataset)
      model = SPop()
      model.fit(dataset)
      model.score(0, [])
      result = model.rank(0, history_items=[])
      self.assertTrue((result[0] == [3, 2, 4, 1, 0, 5, 8, 7, 6]).all())
  
file_path: cornac/tests/cornac/models/test_recommender.py
imports: import unittest
  from cornac.data import BasketDataset, Dataset, SequentialDataset, Reader
  from cornac.models import MF, GPTop, SPop, NextBasketRecommender, NextItemRecommender
label_desc: Use image node_id 3 for calling the TestNextItemRecommender obj's underlying member method code with example usage: obj.test_fit() without return types