Add simple update test to pfq.

bin/cros_au_test_harness.py

 #!/usr/bin/python
 
 # Copyright (c) 2010 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.
 
 import optparse
 import os
 import re
 import sys
@@ skipping 340 matching lines @@
           if self.data_size > (2 * 1024 * 1024):
             self.delay_count += 1
             time.sleep(20)
 
         self.data_size += len(data)
         return data
 
     self._AttemptUpdateWithFilter(DelayedFilter())
 
   def SimpleTest(self):
-    """A simple update  that updates the target image to itself.
+    """A simple update that updates once from a base image to a target.
 
     We explicitly don't use test prefix so that isn't run by default.  Can be
     run using test_prefix option.
     """
-    self.PrepareBase(target_image_path)
+    self.PrepareBase(base_image_path)
     self.UpdateImage(target_image_path)
     self.VerifyImage(100)
 
 
 class RealAUTest(unittest.TestCase, AUTest):
   """Test harness for updating real images."""
 
   def setUp(self):
     AUTest.setUp(self)
 
@@ skipping 250 matching lines @@
   elif options.type == 'real': test_class = RealAUTest
   else: parser.error('Could not parse harness type %s.' % options.type)
 
   remote = options.remote
 
   test_suite = test_loader.loadTestsFromTestCase(test_class)
   test_result = unittest.TextTestRunner(verbosity=2).run(test_suite)
 
   if not test_result.wasSuccessful():
     Die('Test harness was not successful')