code: def test_has_eulerian_path_directed_graph(self):
      # Test directed graphs and returns False
      G = nx.DiGraph()
      G.add_edges_from([(0, 1), (1, 2), (0, 2)])
      assert not nx.has_eulerian_path(G)
  
      # Test directed graphs without isolated node returns True
      G = nx.DiGraph()
      G.add_edges_from([(0, 1), (1, 2), (2, 0)])
      assert nx.has_eulerian_path(G)
  
      # Test directed graphs with isolated node returns False
      G.add_node(3)
      assert not nx.has_eulerian_path(G)
  
imports: import collections
  import pytest
  import networkx
label_desc: Use image node_id 3 for calling the TestHasEulerianPath obj's underlying member method code with example usage: obj.test_has_eulerian_path_directed_graph() without return types