class_docstr: Mixin to test a bunch of common functionality in models
  deriving from RecommenderBase
code: def test_serialization_without_fit(self):
      model = self._get_model()
      with tempfile.TemporaryDirectory() as tmpdir:
          filename = os.path.join(tmpdir, "model.npz")
          model.save(filename)
          reloaded = model.load(filename)
          assert model.__dict__ == reloaded.__dict__
  
imports: import os
  import pickle
  import random
  import tempfile
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from scipy.sparse import coo_matrix, csr_matrix
  from implicit.evaluation import precision_at_k
  from implicit.nearest_neighbours import ItemItemRecommender
  from implicit.utils import ParameterWarning
label_desc: Use image node_id 22 for calling the RecommenderBaseTestMixin obj's underlying member method code with example usage: obj.test_serialization_without_fit() without return types