Make test_net_info a bit more robust.

infra/services/sysmon/system_metrics.py

 # Copyright (c) 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import errno
 import os
 import logging
 import time
 
 import psutil
@@ skipping 125 matching lines @@
       raise
 
 
 def get_mem_info():
   # We don't report mem.used because (due to virtual memory) it is not useful.
   mem = psutil.virtual_memory()
   mem_free.set(mem.available)
   mem_total.set(mem.total)
 
 
-def get_net_info(): # pragma: no cover
+def get_net_info():
   metric_counter_names = [
       (net_up, 'bytes_sent'),
       (net_down, 'bytes_recv'),
       (net_err_up, 'errout'),
       (net_err_down, 'errin'),
       (net_drop_up, 'dropout'),
       (net_drop_down, 'dropin'),
   ]
 
   nics = psutil.net_io_counters(pernic=True)
@@ skipping 19 matching lines @@
     except OSError:  # pragma: no cover
       pass
     else:
       load_average.set(avg1, fields={'minutes': 1})
       load_average.set(avg5, fields={'minutes': 5})
       load_average.set(avg15, fields={'minutes': 15})
 
 
 def get_unix_time():
   unix_time.set(int(time.time() * 1000))