old_contents: import pytest
  
  import compas
  from compas.datastructures import Network
  
  
  @pytest.fixture
  def k5_network():
      network = Network()
      network.add_edge('a', 'b')
      network.add_edge('a', 'c')
      network.add_edge('a', 'd')
      network.add_edge('a', 'e')
  
      network.add_edge('b', 'c')
      network.add_edge('b', 'd')
      network.add_edge('b', 'e')
  
      network.add_edge('c', 'd')
      network.add_edge('c', 'e')
  
      network.add_edge('d', 'e')
  
      return network
  
  
  def test_add_node():
      network = Network()
      assert network.add_node(1) == 1
      assert network.add_node('1', x=0, y=0, z=0) == '1'
      assert network.add_node(2) == 2
      assert network.add_node(0, x=1) == 0
  
  
  def test_non_planar(k5_network):
      if compas.IPY:
          return
  
      from compas.datastructures import network_is_planar
      assert network_is_planar(k5_network) is not True
  
  
  def test_planar(k5_network):
      if compas.IPY:
          return
  
      from compas.datastructures import network_is_planar
  
      k5_network.delete_edge('a', 'b')  # Delete (a, b) edge to make K5 planar
      assert network_is_planar(k5_network) is True
  
new_contents: import pytest
  
  from compas.datastructures import Network
  
  
  @pytest.fixture
  def k5_network():
      network = Network()
      network.add_edge('a', 'b')
      network.add_edge('a', 'c')
      network.add_edge('a', 'd')
      network.add_edge('a', 'e')
  
      network.add_edge('b', 'c')
      network.add_edge('b', 'd')
      network.add_edge('b', 'e')
  
      network.add_edge('c', 'd')
      network.add_edge('c', 'e')
  
      network.add_edge('d', 'e')
  
      return network
  
  
  def test_add_node():
      network = Network()
      assert network.add_node(1) == 1
      assert network.add_node('1', x=0, y=0, z=0) == '1'
      assert network.add_node(2) == 2
      assert network.add_node(0, x=1) == 0
  
  
  def test_non_planar(k5_network):
      try:
          import planarity  # noqa: F401
      except ImportError:
          return
  
      from compas.datastructures import network_is_planar
      assert network_is_planar(k5_network) is not True
  
  
  def test_planar(k5_network):
      try:
          import planarity  # noqa: F401
      except ImportError:
          return
  
      from compas.datastructures import network_is_planar
  
      k5_network.delete_edge('a', 'b')  # Delete (a, b) edge to make K5 planar
      assert network_is_planar(k5_network) is True
  
subject: update tests