clean up ip_command interface

- In change I16b180a298e104f393b5f665409cdf4ba5bff203 an
  error was introduced i how _get_impl was defiend in
  os_vif/internal/command/ip/api.py. This change correct
  the error by returning a instance of the the PyRoute2
  class instead of a reference to the enclosing module.
- This change adds exists to the ip command interfece.
- This change makes the windows version also inherit from
  the ip_command abstract base class.

Closes-Bug: #1797182
Change-Id: I82377297db9e9ff7fad055dadb73864964f427d9

os_vif/internal/command/ip/api.py

@@ -23,6 +23,6 @@ LOG = logging.getLogger(__name__)
 
 def _get_impl():
     if os.name == 'nt':
-        return win_ip_lib
+        return win_ip_lib.Netifaces()
     else:
-        return linux_ip_lib
+        return linux_ip_lib.PyRoute2()

os_vif/internal/command/ip/ip_command.py

@@ -59,3 +59,11 @@ class IpCommand(object):
         :param   dev_type: String network device type (TYPE_VETH, TYPE_VLAN)
         :return: status of the command execution
         """
+
+    @abc.abstractmethod
+    def exists(self, device):
+        """Method to dectect if a device exists.
+
+        :param   device: A network device (string)
+        :return: True if device exists else False
+        """

os_vif/internal/command/ip/windows/impl_netifaces.py

@@ -17,29 +17,30 @@ import netifaces
 from oslo_log import log as logging
 
 from os_vif import exception
-
+from os_vif.internal.command.ip import ip_command
 
 LOG = logging.getLogger(__name__)
 
 
-def exists(device):
-    """Return True if the device exists in the namespace."""
-    try:
-        return bool(netifaces.ifaddresses(device))
-    except ValueError:
-        LOG.warning("The device does not exist on the system: %s", device)
-    except OSError:
-        LOG.error("Failed to get interface addresses: %s", device)
-    return False
+class Netifaces(ip_command.IpCommand):
 
+    def exists(self, device):
+        """Return True if the device exists in the namespace."""
+        try:
+            return bool(netifaces.ifaddresses(device))
+        except ValueError:
+            LOG.warning("The device does not exist on the system: %s", device)
+        except OSError:
+            LOG.error("Failed to get interface addresses: %s", device)
+            return False
 
-def set(*args):
-    exception.NotImplementedForOS(function='ip.set', os='Windows')
+    def set(self, device, check_exit_code=None, state=None, mtu=None,
+            address=None, promisc=None):
+        exception.NotImplementedForOS(function='ip.set', os='Windows')
 
+    def add(self, device, dev_type, check_exit_code=None, peer=None, link=None,
+            vlan_id=None):
+        exception.NotImplementedForOS(function='ip.add', os='Windows')
 
-def add(*args):
-    exception.NotImplementedForOS(function='ip.add', os='Windows')
-
-
-def delete(*args):
-    exception.NotImplementedForOS(function='ip.delete', os='Windows')
+    def delete(self, device, check_exit_code=None):
+        exception.NotImplementedForOS(function='ip.delete', os='Windows')

os_vif/tests/unit/internal/command/ip/test_api.py

@@ -0,0 +1,32 @@
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import mock
+
+from os_vif.tests.unit import base
+
+from os_vif.internal.command.ip import api
+from os_vif.internal.command.ip.linux import impl_pyroute2 as linux_ip_lib
+from os_vif.internal.command.ip.windows import impl_netifaces as win_ip_lib
+
+
+class TestIpApi(base.TestCase):
+
+    @mock.patch("os.name", "nt")
+    def test_get_impl_windows(self):
+        ip_lib = api._get_impl()
+        self.assertIsInstance(ip_lib, win_ip_lib.Netifaces)
+
+    @mock.patch("os.name", "posix")
+    def test_get_impl_linux(self):
+        ip_lib = api._get_impl()
+        self.assertIsInstance(ip_lib, linux_ip_lib.PyRoute2)

os_vif/tests/unit/internal/command/ip/windows/test_impl_netifaces.py

@@ -23,22 +23,23 @@ class TestIPDevice(base.TestCase):
         super(TestIPDevice, self).setUp()
         self.device_name = 'test_device'
         self.mock_log = mock.patch.object(ip_lib, "LOG").start()
+        self.ip_lib = ip_lib.Netifaces()
 
     @mock.patch.object(netifaces, 'ifaddresses', return_value=True)
     def test_exists(self, mock_ifaddresses):
-        self.assertTrue(ip_lib.exists(self.device_name))
+        self.assertTrue(self.ip_lib.exists(self.device_name))
         mock_ifaddresses.assert_called_once_with(self.device_name)
 
     @mock.patch.object(netifaces, 'ifaddresses', side_effect=ValueError())
     def test_exists_not_found(self, mock_ifaddresses):
-        self.assertFalse(ip_lib.exists(self.device_name))
+        self.assertFalse(self.ip_lib.exists(self.device_name))
         mock_ifaddresses.assert_called_once_with(self.device_name)
         self.mock_log.warning.assert_called_once_with(
             "The device does not exist on the system: %s", self.device_name)
 
     @mock.patch.object(netifaces, 'ifaddresses', side_effect=OSError())
     def test_exists_os_error_exception(self, mock_ifaddresses):
-        self.assertFalse(ip_lib.exists(self.device_name))
+        self.assertFalse(self.ip_lib.exists(self.device_name))
         mock_ifaddresses.assert_called_once_with(self.device_name)
         self.mock_log.error.assert_called_once_with(
             "Failed to get interface addresses: %s", self.device_name)