Avoid race condition on creating directory by pre-creating early.

bin/au_test_harness/cros_au_test_harness.py

 #!/usr/bin/python
 
 # Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This module runs a suite of Auto Update tests.
 
   The tests can be run on either a virtual machine or actual device depending
   on parameters given.  Specific tests can be run by invoking --test_prefix.
@@ skipping 257 matching lines @@
     assert options.public_key and os.path.exists(options.public_key), \
         error_msg % 'public'
     _InsertPublicKeyIntoImage(options.target_image, options.public_key)
     if options.target_image != options.base_image:
       _InsertPublicKeyIntoImage(options.base_image, options.public_key)
     options.clean = True
 
   # Clean up previous work if requested.
   if options.clean: _CleanPreviousWork(options)
 
+  # Make sure we have a log directory.
+  if not os.path.exists(options.test_results_root):
+    os.makedirs(options.test_results_root)
+
   # Generate cache of updates to use during test harness.
   update_cache = _PregenerateUpdates(options)
   au_worker.AUWorker.SetUpdateCache(update_cache)
 
   my_server = dev_server_wrapper.DevServerWrapper(
       au_test.AUTest.test_results_root)
   my_server.start()
   try:
     if options.type == 'vm':
       _RunTestsInParallel(options)
     else:
       # TODO(sosa) - Take in a machine pool for a real test.
       # Can't run in parallel with only one remote device.
       test_suite = _PrepareTestSuite(options)
       test_result = unittest.TextTestRunner(verbosity=2).run(test_suite)
       if not test_result.wasSuccessful(): cros_lib.Die('Test harness failed.')
   finally:
     my_server.Stop()
 
 
 if __name__ == '__main__':
   main()