new_contents: #!/usr/bin/env python3
  #
  # Copyright (C) 2019-2020 VyOS maintainers and contributors
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU General Public License version 2 or later as
  # published by the Free Software Foundation.
  #
  # This program is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  # GNU General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  import re
  import os
  import unittest
  
  from psutil import process_iter
  from vyos.configsession import ConfigSession, ConfigSessionError
  from vyos.util import read_file
  
  config_file = '/etc/ppp/peers/{}'
  base_path = ['interfaces', 'pppoe']
  
  def get_config_value(interface, key):
      with open(config_file.format(interface), 'r') as f:
          for line in f:
              if line.startswith(key):
                  return list(line.split())
      return []
  
  class PPPoEInterfaceTest(unittest.TestCase):
      def setUp(self):
          self.session = ConfigSession(os.getpid())
          self._interfaces = ['pppoe0', 'pppoe1', 'pppoe2']
  
      def tearDown(self):
          self.session.delete(base_path)
          self.session.commit()
          del self.session
  
      def test_pppoe_1(self):
          """ Check if PPPoE dialer can be configured and runs """
          # ensure source-interface is available
          source_interface = 'eth0'
          self.session.set(['interfaces', 'ethernet', source_interface])
  
          for interface in self._interfaces:
              user = 'VyOS-user-' + interface
              passwd = 'VyOS-passwd-' + interface
  
              self.session.set(base_path + [interface, 'authentication', 'user', user])
              self.session.set(base_path + [interface, 'authentication', 'password', passwd])
              self.session.set(base_path + [interface, 'default-route', 'auto'])
              self.session.set(base_path + [interface, 'mtu', '1400'])
              self.session.set(base_path + [interface, 'no-peer-dns'])
  
              # check validate() - a source-interface is required
              with self.assertRaises(ConfigSessionError):
                  self.session.commit()
              self.session.set(base_path + [interface, 'source-interface', 'eth0'])
  
              # commit changes
              self.session.commit()
  
          # verify configuration file(s)
          for interface in self._interfaces:
              user = 'VyOS-user-' + interface
              password = 'VyOS-passwd-' + interface
  
              cur_mtu = get_config_value(interface, 'mtu')[1]
              cur_user = get_config_value(interface, 'user')[1].replace('"', '')
              cur_password = get_config_value(interface, 'password')[1].replace('"', '')
              cur_default_route = get_config_value(interface, 'defaultroute')[0]
              cur_ifname = get_config_value(interface, 'ifname')[1]
  
              self.assertTrue(cur_mtu == '1400')
              self.assertTrue(cur_user == user)
              self.assertTrue(cur_password == password)
              self.assertTrue(cur_default_route == 'defaultroute')
              self.assertTrue(cur_ifname == interface)
  
              # Check if ppp process is running in the interface in question
              running = False
              for p in process_iter():
                  if "pppd" in p.name():
                      if interface in p.cmdline():
                          running = True
  
              self.assertTrue(running)
  
  if __name__ == '__main__':
      unittest.main()
  
subject: add initial test