Make test_net_info a bit more robust.

infra_libs/ts_mon/common/metric_store.py

 # Copyright 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 collections
 import copy
+import itertools
 import threading
 import time
 
 from infra_libs.ts_mon.common import errors
 
 
 """A light-weight representation of a set or an incr.
 
 Args:
   name: The metric name.
@@ skipping 180 matching lines @@
   def set_value(self, fields, target_fields, value):
     self.get_target_values(target_fields).set_value(fields, value)
 
   def iter_targets(self):
     # Make a copy of the values in case another thread (or this
     # generator's consumer) modifies them while we're iterating.
     with self._thread_lock:
       values = copy.copy(self._values)
     for target_fields, fields_values in values.iteritems():
       target = copy.copy(self._store._state.target)
-      target.update({k: v for k, v in target_fields})
+      if target_fields:
+        target.update({k: v for k, v in target_fields})
       yield target, fields_values
 
 
 class MetricValues(object):
   def __init__(self, store, start_time):
     self._start_time = start_time
     self._values = TargetFieldsValues(store)
 
   @property
   def start_time(self):
@@ skipping 21 matching lines @@
 
   def _entry(self, name):
     if name not in self._values:
       self._reset(name)
 
     return self._values[name]
 
   def get(self, name, fields, target_fields, default=None):
     return self._entry(name).get_value(fields, target_fields, default)
 
+  def iter_field_values(self, name):
+    return itertools.chain.from_iterable(
+        x.iteritems() for _, x in self._entry(name).values.iter_targets())
+
   def get_all(self):
     # Make a copy of the metric values in case another thread (or this
     # generator's consumer) modifies them while we're iterating.
     with self._thread_lock:
       values = copy.copy(self._values)
 
     for name, metric_values in values.iteritems():
       if name not in self._state.metrics:
         continue
       start_time = metric_values.start_time
@@ skipping 27 matching lines @@
 
   def reset_for_unittest(self, name=None):
     if name is not None:
       self._reset(name)
     else:
       for name in self._values.keys():
         self._reset(name)
 
   def _reset(self, name):
     self._values[name] = MetricValues(self, self._start_time(name))