make version of ts_mon compatible with appengine

infra_libs/ts_mon/common/test/helpers_test.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 unittest
 
 import mock
 
-from infra_libs.ts_mon import helpers
-from infra_libs.ts_mon import metrics
+try:
+  from infra_libs.ts_mon.common import metrics
+  from infra_libs.ts_mon.common import helpers
+except ImportError: # pragma: no cover
+  from common import metrics
+  from common import helpers
 
 
 class ScopedIncrementCounterTest(unittest.TestCase):
 
   def test_success(self):
     counter = mock.Mock(metrics.CounterMetric)
     with helpers.ScopedIncrementCounter(counter):
       pass
     counter.increment.assert_called_once_with({'status': 'success'})
 
@@ skipping 36 matching lines @@
     with helpers.ScopedIncrementCounter(counter, 'a', 'b', 'c'):
       pass
     counter.increment.assert_called_once_with({'a': 'b'})
 
   def test_custom_label_exception(self):
     counter = mock.Mock(metrics.CounterMetric)
     with self.assertRaises(Exception):
       with helpers.ScopedIncrementCounter(counter, 'a', 'b', 'c'):
         raise Exception()
     counter.increment.assert_called_once_with({'a': 'c'})