new_contents: #!/usr/bin/env python
  
  from mininet.cli import CLI
  from mininet.link import Link
  from mininet.net import Mininet
  from mininet.node import RemoteController
  from mininet.term import makeTerm
  
  if '__main__' == __name__:
      net = Mininet(controller=RemoteController)
  
      c0 = net.addController('c0')
  
      s1 = net.addSwitch('s1')
      s2 = net.addSwitch('s2')
  
      Link(s1, s2)
      Link(s1, s2)
  
      net.build()
      c0.start()
      s1.start([c0])
      s2.start([c0])
  
      s1.cmd('ovs-vsctl set Bridge s1 protocols=OpenFlow13')
      s2.cmd('ovs-vsctl set Bridge s2 protocols=OpenFlow13')
  
      CLI(net)
  
      net.stop()
  
subject: test tool: add a script to make the test environment on mininet