code: def test_fit(self, setup, kg, sampler, is_inverse, is_split):
      sampler = sampler(is_inverse, is_split)
      assert len(sampler._counts) == 0
      sampler.fit(kg)
      if isinstance(sampler, ObjFreqSampler):
          if kg == KG_LOOP:
              assert len(sampler._counts) == 3
          else:
              assert len(sampler._counts) == 9
      elif isinstance(sampler, ObjPredFreqSampler):
          if kg == KG_LOOP:
              assert len(sampler._counts) == 3
          else:
              assert len(sampler._counts) == 8
      else:
          if kg == KG_LOOP:
              assert len(sampler._counts) == 2
          else:
              assert len(sampler._counts) == 1
  
file_path: pyRDF2Vec/tests/samplers/test_frequency.py
imports: import itertools
  import pytest
  from pyrdf2vec.graphs import KG, Vertex
  from pyrdf2vec.samplers import ObjFreqSampler, ObjPredFreqSampler, PredFreqSampler
label_desc: Use image node_id 3 for calling the TestFreqSampler obj's underlying member method code with example usage: obj.test_fit(setup, kg, sampler, is_inverse, is_split) without return types