XenAPI: add unit test for plugin bandwidth

Add unit test for plugin bandwidth. And there is a bug in
the plugin which does not close the opened file. This change
will try to fix it. It also splits _read_proc_net() into two
functions, so that it's easier to make the UT.

Change-Id: Ie871b1d16cf180e9709e46bb0d67573053d14376

nova/tests/unit/virt/xenapi/plugins/test_bandwidth.py

@@ -0,0 +1,49 @@
+# Copyright (c) 2016 OpenStack Foundation
+# All Rights Reserved.
+#
+#    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.
+
+from nova.tests.unit.virt.xenapi.plugins import plugin_test
+
+
+class BandwidthTestCase(plugin_test.PluginTestBase):
+    def setUp(self):
+        super(BandwidthTestCase, self).setUp()
+        self.pluginlib = self.load_plugin("pluginlib_nova.py")
+
+        # Prevent any logging to syslog
+        self.mock_patch_object(self.pluginlib,
+                               'configure_logging')
+
+        self.bandwidth = self.load_plugin("bandwidth")
+
+    def test_get_bandwitdth_from_proc(self):
+        fake_data = ['Inter-|   Receive  |  Transmit',
+        'if|bw_in i1 i2 i3 i4 i5 i6 i7|bw_out o1 o2 o3 o4 o5 o6 o7',
+        'xenbr1: 1 0 0 0 0 0 0 0 11 0 0 0 0 0 0 0',
+        'vif2.0: 2 0 0 0 0 0 0 0 12 0 0 0 0 0 0 0',
+        'vif2.1: 3 0 0 0 0 0 0 0 13 0 0 0 0 0 0 0\n']
+        expect_devmap = {'2': {'1': {'bw_in': 13, 'bw_out': 3},
+                               '0': {'bw_in': 12, 'bw_out': 2}
+                              }
+                        }
+
+        mock_read_proc_net = self.mock_patch_object(
+            self.bandwidth,
+            '_read_proc_net',
+            return_val=fake_data)
+
+        devmap = self.bandwidth._get_bandwitdth_from_proc()
+
+        self.assertTrue(mock_read_proc_net.called)
+        self.assertEqual(devmap, expect_devmap)

plugins/xenserver/xenapi/etc/xapi.d/plugins/bandwidth

@@ -29,8 +29,16 @@ pluginlib_nova.configure_logging('bandwidth')
 
 
 def _read_proc_net():
-    devs = [l.strip() for l in open('/proc/net/dev', 'r').readlines()]
-    # Ignore headers
+    f = open('/proc/net/dev', 'r')
+    try:
+        return f.readlines()
+    finally:
+        f.close()
+
+
+def _get_bandwitdth_from_proc():
+    devs = [l.strip() for l in _read_proc_net()]
+    # ignore headers
     devs = devs[2:]
     dlist = [d.split(':', 1) for d in devs if d.startswith('vif')]
     devmap = dict()
@@ -46,7 +54,7 @@ def _read_proc_net():
 
 
 def fetch_all_bandwidth(session):
-    return _read_proc_net()
+    return _get_bandwitdth_from_proc()
 
 
 if __name__ == '__main__':