code: def test_single_linkage_clustering():
      # Check that we get the correct result in two emblematic cases
      moons, moon_labels = make_moons(noise=0.05, random_state=42)
      clustering = AgglomerativeClustering(
          n_clusters=2, linkage="single"
      )
      clustering.fit(moons)
      assert_almost_equal(
          normalized_mutual_info_score(clustering.labels_, moon_labels),
          1,
      )
  
      circles, circle_labels = make_circles(
          factor=0.5, noise=0.025, random_state=42
      )
      clustering = AgglomerativeClustering(
          n_clusters=2, linkage="single"
      )
      clustering.fit(circles)
      assert_almost_equal(
          normalized_mutual_info_score(
              clustering.labels_, circle_labels
          ),
          1,
      )
  
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 10 for calling a global function with example usage: test_single_linkage_clustering() without return types