Fix errors in PrefixDelegation.remove_stale_ri_ifname

Firstly fix a typo (iteriterms -> iteritems) introduced by [1]. Then a
"dictionary changed size during iteration" RuntimeError is reported by
the newly added unit test.

[1] I17df98128c7a88e72e31251687f30f569df6b860.

TrivialFix

Change-Id: I70c548eab2264b3f94ba1a215f933046345411a7
Signed-off-by: Hunt Xu <mhuntxu@gmail.com>

neutron/agent/linux/pd.py

@@ -191,10 +191,14 @@ class PrefixDelegation(object):
     def remove_stale_ri_ifname(self, router_id, stale_ifname):
         router = self.routers.get(router_id)
         if router is not None:
-            for subnet_id, pd_info in six.iteriterms(router['subnets']):
+            subnet_to_delete = None
+            for subnet_id, pd_info in six.iteritems(router['subnets']):
                 if pd_info.ri_ifname == stale_ifname:
                     self._delete_pd(router, pd_info)
-                    del router['subnets'][subnet_id]
+                    subnet_to_delete = subnet_id
+                    break
+            if subnet_to_delete:
+                del router['subnets'][subnet_to_delete]
 
     @staticmethod
     def _get_lla(mac):

neutron/tests/unit/agent/linux/test_pd.py

@@ -93,3 +93,23 @@ class TestPrefixDelegation(tests_base.DietTestCase):
         with mock.patch.object(pd.LOG, 'exception') as log:
             pd.update_router(None, None, l3_agent, router=router)
             self.assertTrue(log.called)
+
+    def test_remove_stale_ri_ifname(self):
+        pd_info_1 = mock.Mock()
+        pd_info_1.ri_ifname = 'STALE'
+        pd_info_2 = mock.Mock()
+        pd_info_2.ri_ifname = 'NOT_STALE'
+        router = {
+            'subnets': {
+                'FAKE_SUBNET_ID1': pd_info_1,
+                'FAKE_SUBNET_ID2': pd_info_2}}
+
+        class FakePD(pd.PrefixDelegation):
+            def __init__(self, router):
+                self.routers = {'FAKE_ROUTER_ID': router}
+
+        fake_pd = FakePD(router)
+        fake_pd._delete_pd = mock.Mock()
+        fake_pd.remove_stale_ri_ifname('FAKE_ROUTER_ID', 'STALE')
+        fake_pd._delete_pd.assert_called_with(router, pd_info_1)
+        self.assertEqual(len(router['subnets'].keys()), 1)