class_docstr: Unit tests for the
  :func:`~networkx.algorithms.matching.is_matching` function.
code: def test_single_edge(self):
      G = nx.path_graph(4)
      assert nx.is_matching(G, {(1, 2)})
  
imports: import math
  from itertools import permutations
  from pytest import raises
  import networkx
  from networkx.algorithms.matching import matching_dict_to_set
  from networkx.utils import edges_equal
label_desc: Use image node_id 3 for calling the TestIsMatching obj's underlying member method code with example usage: obj.test_single_edge() without return types