old_contents: #!/usr/bin/env python
  from __future__ import print_function
  from __future__ import unicode_literals
  from simple_graph import Graph
  
  
  def test_init():
      assert Graph().graph == {}
  
  
  def test_add_node():
      g = Graph()
      g.add_node("A")
      assert "A" in g.graph
      assert g.graph["A"] == []
      g.add_node("B")
      assert "B" in g.graph
      assert g.graph["B"] == []
  
  
  def test_nodes():
      g = Graph()
      assert g.nodes() == []
      g.add_node("A")
      g.add_node("B")
      assert "A" and "B" in g.graph
  
  
  def test_add_edge(value1, value2):
  
  
  # def test_edges():
  #     return edges
  
  
  # def test_del_node(value):
  #     return
  
  
  # def test_has_node(value):
  #     return
  
  
  # def test_neighbors(value):
  #     return neighbors
  
  
  # def test_adjecent(value, value2):
  #     return condition
  
new_contents: #!/usr/bin/env python
  from simple_graph import Graph
  import pytest
  
  
  def test_init():
      assert Graph().graph == {}
  
  
  def test_add_node():
      g = Graph()
      g.add_node("A")
      assert "A" in g.graph
      assert g.graph["A"] == []
      g.add_node("B")
      assert "B" in g.graph
      assert g.graph["B"] == []
  
  
  def test_nodes():
      g = Graph()
      assert g.nodes() == []
      g.add_node("A")
      g.add_node("B")
      assert "A" and "B" in g.graph
  
  
  def test_add_edge():
      g = Graph()
      g.add_edge("A", "B")
      assert "A" in g.graph
      assert "B" in g.graph
      assert "B" in g.graph["A"]
      g.add_edge("A", "C")
      assert "C" in g.graph
      assert "C" in g.graph["A"]
      g.add_edge("D", "B")
      assert "D" in g.graph
      assert "B" in g.graph["D"]
  
  
  def test_edges():
      g = Graph()
      assert [] == g.edges()
      g.add_edge("A", "B")
      assert ("A", "B") in g.edges()
      g.add_edge("A", "C")
      assert ("A", "C") in g.edges()
      g.add_edge("B", "A")
      assert ("B", "A") in g.edges()
      g.add_edge("D", "B")
      assert ("D", "B") in g.edges()
  
  
  def test_del_node():
      g = Graph()
      with pytest.raises(KeyError):
          g.del_node("A")
  
      g.add_node("A")
      g.del_node("A")
      assert "A" not in g.graph
  
      g.add_edge("A", "B")
      g.del_node("A")
      assert "A" not in g.graph
      assert "B" in g.graph
      assert ("A", "B") not in g.edges()
  
      g.add_edge("A", "B")
      g.del_node("B")
      assert "B" not in g.graph
      assert "A" in g.graph
      assert ("A", "B") not in g.edges()
  
  
  def test_has_node():
      g = Graph()
      assert g.has_node("A") is False
      g.add_node("A")
      assert g.has_node("A") is True
      assert g.has_node("B") is False
  
  
  
  # def test_neighbors(value):
  #     return neighbors
  
  
  # def test_adjecent(value, value2):
  #     return condition
  
subject: add add_edge, edges, del_node, has_node tests.