code: def test_affinity_passed_to_fix_connectivity():
      # Test that the affinity parameter is actually passed to the pairwise
      # function
  
      size = 2
      rng = np.random.RandomState(0)
      X = rng.randn(size, size)
      mask = np.array([True, False, False, True])
  
      connectivity = grid_to_graph(
          n_x=size, n_y=size, mask=mask, return_as=np.ndarray
      )
  
      class FakeAffinity:
          def __init__(self):
              self.counter = 0
  
          def increment(self, *args, **kwargs):
              self.counter += 1
              return self.counter
  
      fa = FakeAffinity()
  
      linkage_tree(X, connectivity=connectivity, affinity=fa.increment)
  
      assert fa.counter == 3
  
imports: import itertools
  import shutil
  from functools import partial
  from tempfile import mkdtemp
  import numpy
  import pytest
  from scipy.cluster import hierarchy
  from scipy.sparse.csgraph import connected_components
  from sklearn.cluster import AgglomerativeClustering, FeatureAgglomeration, ward_tree
  from sklearn.cluster._agglomerative import _TREE_BUILDERS, _fix_connectivity, _hc_cut, linkage_tree
  from sklearn.cluster._hierarchical_fast import average_merge, max_merge, mst_linkage_core
  from sklearn.datasets import make_circles, make_moons
  from sklearn.feature_extraction.image import grid_to_graph
  from sklearn.metrics import DistanceMetric
  from sklearn.metrics.cluster import adjusted_rand_score, normalized_mutual_info_score
  from sklearn.metrics.pairwise import PAIRED_DISTANCES, cosine_distances, manhattan_distances, pairwise_distances
  from sklearn.metrics.tests.test_dist_metrics import METRICS_DEFAULT_PARAMS
  from sklearn.neighbors import kneighbors_graph
  from sklearn.utils._fast_dict import IntFloatDict
  from sklearn.utils._testing import assert_almost_equal, assert_array_almost_equal, assert_array_equal, create_memmap_backed_data, ignore_warnings
  from sklearn.utils.fixes import LIL_CONTAINERS
label_desc: Use image node_id 25 for calling a global function with example usage: test_affinity_passed_to_fix_connectivity() and returns: self