[PowerProfiler] Make sure correct version of pySerial is imported with monsoon profiler.

tools/telemetry/telemetry/core/util_unittest.py

 # Copyright 2012 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 os
 import unittest
 import shutil
+import sys
 import tempfile
 
 from telemetry.core import util
 
 class TestWait(unittest.TestCase):
   @staticmethod
   def testNonTimeout():
     def test():
       return True
     util.WaitFor(test, 0.1)
@@ skipping 38 matching lines @@
       with open(
           os.path.join(self.test_directory, 'test_%03d.json' % i), 'w') as _:
         pass
     next_json_test_file_path = util.GetSequentialFileName(
         os.path.join(self.test_directory, 'test'))
     self.assertEquals(os.path.join(self.test_directory, 'test_003'),
                       next_json_test_file_path)
 
   def tearDown(self):
     shutil.rmtree(self.test_directory)
+
+class PySerialVersionTest(unittest.TestCase):

[tonyg, 2014/06/11 15:44:00]

This is getting convoluted. Stepping back, what you really care about is that
monsoon has a new enough pyserial to work properly.

So let's just drop this test and verify that by adding "assert
float(serial.VERSION) >= 2.7, 'Monsoon requires pyserial version 2.7 or later.
You have %s' % serial.VERSION" to monsoon.py's __init__ method.

With that, I think this patch will be ready to land.

+  def testPySerialVersion(self):
+    third_party_pyserial_path = os.path.abspath(\
+      os.path.join(util.GetTelemetryDir(), 'third_party', 'pyserial'))
+
+    # Make an explicit call to sys.path.insert(0,...) to make sure the serial
+    # library is indeed from third_party/pyserial
+    sys.path.insert(0, third_party_pyserial_path)
+    import serial
+    third_party_pyserial_version = serial.VERSION
+
+    # Remove all traces of third_party_pyserial_path from the sys.path
+    while sys.path.count(third_party_pyserial_path):
+      sys.path.remove(third_party_pyserial_path)
+
+    try:
+      # Try to load serial from the system library if its available
+      reload(serial)
+      system_library_version = serial.VERSION
+
+      # The version number may or may not match but we can safely ignore it
+      self.assertEqual(system_library_version, third_party_pyserial_version)
+    except AssertionError:
+      # Ignoring both cases
+      # 1. Serial not being part of any system library
+      # 2. Version number mismatch
+      pass
+
+    util.AddDirToPythonPath(third_party_pyserial_path)
+    reload(serial)
+    self.assertEqual(serial.VERSION, third_party_pyserial_version)