From 2eb5fcfa506e0d0967d8f91d20ba6686749c59a0 Mon Sep 17 00:00:00 2001
From: Hui HX Xiang <xianghui@cn.ibm.com>
Date: Fri, 11 Oct 2013 21:45:45 -0700
Subject: [PATCH] Add error log for SystemExit in dhcp-agent

The SystemExit exception should be logged in dhcp-agent, the
operator may miss the useful exception messages to debug.

* Add error log for SystemExit in dhcp-agent.
* Add addCleanup(mock.patch.stopall) in setup()
* Remove teardown()
* Add unit test for None and nonexistent interface_driver.

Closes-Bug #1239030

Change-Id: I01bef69adecaaf8d8a919034d33c60a43e4469a7
---
 neutron/agent/linux/dhcp.py           |  5 ++++-
 neutron/tests/unit/test_dhcp_agent.py | 26 ++++++++++++++++++++------
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/neutron/agent/linux/dhcp.py b/neutron/agent/linux/dhcp.py
index 9e7481d7c4..277eccba6e 100644
--- a/neutron/agent/linux/dhcp.py
+++ b/neutron/agent/linux/dhcp.py
@@ -553,7 +553,9 @@ class DeviceManager(object):
         self.root_helper = root_helper
         self.plugin = plugin
         if not conf.interface_driver:
-            raise SystemExit(_('You must specify an interface driver'))
+            msg = _('An interface driver must be specified')
+            LOG.error(msg)
+            raise SystemExit(msg)
         try:
             self.driver = importutils.import_object(
                 conf.interface_driver, conf)
@@ -561,6 +563,7 @@ class DeviceManager(object):
             msg = (_("Error importing interface driver '%(driver)s': "
                    "%(inner)s") % {'driver': conf.interface_driver,
                                    'inner': e})
+            LOG.error(msg)
             raise SystemExit(msg)
 
     def get_interface_name(self, network, port):
diff --git a/neutron/tests/unit/test_dhcp_agent.py b/neutron/tests/unit/test_dhcp_agent.py
index 4cc6b2537e..5c9fb3a937 100644
--- a/neutron/tests/unit/test_dhcp_agent.py
+++ b/neutron/tests/unit/test_dhcp_agent.py
@@ -139,12 +139,7 @@ class TestDhcpAgent(base.BaseTestCase):
         self.driver_cls.return_value = self.driver
         self.mock_makedirs_p = mock.patch("os.makedirs")
         self.mock_makedirs = self.mock_makedirs_p.start()
-
-    def tearDown(self):
-        self.driver_cls_p.stop()
-        self.mock_makedirs_p.stop()
-        cfg.CONF.reset()
-        super(TestDhcpAgent, self).tearDown()
+        self.addCleanup(mock.patch.stopall)
 
     def test_dhcp_agent_manager(self):
         state_rpc_str = 'neutron.agent.rpc.PluginReportStateAPI'
@@ -319,6 +314,25 @@ class TestDhcpAgent(base.BaseTestCase):
 
         self.assertEqual(set(networks), set(dhcp.cache.get_network_ids()))
 
+    def test_none_interface_driver(self):
+        cfg.CONF.set_override('interface_driver', None)
+        with mock.patch.object(dhcp, 'LOG') as log:
+            self.assertRaises(SystemExit, dhcp.DeviceManager,
+                              cfg.CONF, 'sudo', None)
+            msg = 'An interface driver must be specified'
+            log.error.assert_called_once_with(msg)
+
+    def test_nonexistent_interface_driver(self):
+        # Temporarily turn off mock, so could use the real import_class
+        # to import interface_driver.
+        self.driver_cls_p.stop()
+        self.addCleanup(self.driver_cls_p.start)
+        cfg.CONF.set_override('interface_driver', 'foo')
+        with mock.patch.object(dhcp, 'LOG') as log:
+            self.assertRaises(SystemExit, dhcp.DeviceManager,
+                              cfg.CONF, 'sudo', None)
+            log.error.assert_called_once()
+
 
 class TestLogArgs(base.BaseTestCase):