mojo: Add isolate test for python bindings test

mojo/tools/pylib/mojo_python_tests_runner.py

 # Copyright 2014 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 argparse
 import json
 import os
 import sys
 import time
 import unittest
@@ skipping 33 matching lines @@
       return 2
 
     chromium_src_dir = os.path.join(os.path.dirname(__file__),
                                     os.pardir,
                                     os.pardir,
                                     os.pardir)
 
     loader = unittest.loader.TestLoader()
     print "Running Python unit tests under %s..." % self._test_dir
 
-    pylib_dir = os.path.join(chromium_src_dir, self._test_dir)
+    pylib_dir = os.path.abspath(os.path.join(chromium_src_dir, self._test_dir))
     if args.tests:
       if pylib_dir not in sys.path:
         sys.path.append(pylib_dir)
       suite = unittest.TestSuite()
       for test_name in args.tests:
         suite.addTests(loader.loadTestsFromName(test_name))
     else:
       suite = loader.discover(pylib_dir, pattern='*_unittest.py')
 
     runner = unittest.runner.TextTestRunner(verbosity=(args.verbose + 1))
@@ skipping 73 matching lines @@
 
 
 def _AddPathToTrie(trie, path, value):
   if TEST_SEPARATOR not in path:
     trie[path] = value
     return
   directory, rest = path.split(TEST_SEPARATOR, 1)
   if directory not in trie:
     trie[directory] = {}
   _AddPathToTrie(trie[directory], rest, value)