code: def test_all():
      sel = basic.AllItemsCandidateSelector()
      sel.fit(simple_df)
  
      assert set(sel.candidates(10)) == set([1, 2, 3])
      assert set(sel.candidates(5)) == set([1, 2, 3])
  
file_path: lkpy/tests/test_candidate_selector.py
imports: from lenskit.algorithms import basic
  import lenskit.util.test
  import pandas
  import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: test_all() without return types