From d4e2752a67edabbefde45e1c82cb6a4fa2d2d012 Mon Sep 17 00:00:00 2001
From: John Garbutt <john.garbutt@rackspace.com>
Date: Wed, 8 Jun 2016 11:31:45 +0100
Subject: [PATCH] Refactor to create _populate_mac_address

To help move the population of the mac addresses, extracting it into a
separate method.

blueprint prep-for-network-aware-scheduling

Change-Id: I4a7c0218b1b841856f44c55e33f3cc9a93cf0461
---
 nova/network/neutronv2/api.py             | 18 ++++++++++-----
 nova/tests/unit/network/test_neutronv2.py | 28 +++++++++++++++++++++++
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/nova/network/neutronv2/api.py b/nova/network/neutronv2/api.py
index 5868a03175fb..014f77939a30 100644
--- a/nova/network/neutronv2/api.py
+++ b/nova/network/neutronv2/api.py
@@ -196,12 +196,8 @@ class API(base_api.NetworkAPI):
             port_req_body['port']['tenant_id'] = instance.project_id
             if security_group_ids:
                 port_req_body['port']['security_groups'] = security_group_ids
-            if available_macs is not None:
-                if not available_macs:
-                    raise exception.PortNotFree(
-                        instance=instance.uuid)
-                mac_address = available_macs.pop()
-                port_req_body['port']['mac_address'] = mac_address
+            mac_address = self._populate_mac_address(
+                instance, port_req_body, available_macs)
             if dhcp_opts is not None:
                 port_req_body['port']['extra_dhcp_opts'] = dhcp_opts
             port = port_client.create_port(port_req_body)
@@ -247,6 +243,16 @@ class API(base_api.NetworkAPI):
                 LOG.exception(_LE('Neutron error creating port on network %s'),
                               network_id, instance=instance)
 
+    @staticmethod
+    def _populate_mac_address(instance, port_req_body, available_macs):
+        if available_macs is not None:
+            if not available_macs:
+                raise exception.PortNotFree(
+                    instance=instance.uuid)
+            mac_address = available_macs.pop()
+            port_req_body['port']['mac_address'] = mac_address
+            return mac_address
+
     def _check_external_network_attach(self, context, nets):
         """Check if attaching to external network is permitted."""
         if not soft_external_network_attach_authorize(context):
diff --git a/nova/tests/unit/network/test_neutronv2.py b/nova/tests/unit/network/test_neutronv2.py
index a99729680eb7..233176a9985f 100644
--- a/nova/tests/unit/network/test_neutronv2.py
+++ b/nova/tests/unit/network/test_neutronv2.py
@@ -4216,6 +4216,34 @@ class TestNeutronv2ExtraDhcpOpts(TestNeutronv2Base):
         self._allocate_for_instance(1, dhcp_options=dhcp_opts)
 
 
+class TestAllocateForInstanceHelpers(test.NoDBTestCase):
+    def test_populate_mac_address_skip_if_none(self):
+        api = neutronapi.API()
+        port_req_body = {}
+
+        api._populate_mac_address(None, port_req_body, None)
+
+        self.assertEqual({}, port_req_body)
+
+    def test_populate_mac_address_raise_if_empty(self):
+        api = neutronapi.API()
+        port_req_body = {}
+        instance = objects.Instance(uuid=uuids.instance)
+
+        self.assertRaises(exception.PortNotFree,
+                          api._populate_mac_address,
+                          instance, port_req_body, [])
+
+    def test_populate_mac_address_adds_last(self):
+        api = neutronapi.API()
+        port_req_body = {'port': {"foo": "bar"}}
+
+        api._populate_mac_address(None, port_req_body, ["a", "b"])
+
+        expected_port = {"foo": "bar", "mac_address": "b"}
+        self.assertEqual(expected_port, port_req_body["port"])
+
+
 class TestNeutronv2NeutronHostnameDNS(TestNeutronv2Base):
     def setUp(self):
         super(TestNeutronv2NeutronHostnameDNS, self).setUp()