Add feature to ctest that allows it to run against the latest image if no latest candidate exists.

ctest/ctest.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.
 
 """Wrapper for tests that are run on builders."""
 
 import fileinput
 import optparse
 import os
 import re
 import sys
 import traceback
 import urllib
 import HTMLParser
 
 import constants
 sys.path.append(constants.SOURCE_ROOT)
 import chromite.lib.cros_build_lib as cros_lib
 
 _IMAGE_TO_EXTRACT = 'chromiumos_test_image.bin'
 _NEW_STYLE_VERSION = '0.9.131.0'
 
+class CrosImageDoesNotExistError(Exception):
+  """Error thrown when no image can be found."""
+  pass
+
+
 class HTMLDirectoryParser(HTMLParser.HTMLParser):
   """HTMLParser for parsing the default apache file index."""
 
   def __init__(self, regex):
     HTMLParser.HTMLParser.__init__(self)
     self.regex_object = re.compile(regex)
     self.link_list = []
 
   def handle_starttag(self, tag, attrs):
     """Overrides from HTMLParser and is called at the start of every tag.
@@ skipping 69 matching lines @@
       return version_b
   return version_a
 
 
 def GetLatestLinkFromPage(url, regex):
   """Returns the latest link from the given url that matches regex.
 
   Args:
     url: Url to download and parse.
     regex: Regular expression to match links against.
+  Raises:
+    CrosImageDoesNotExistError if no image found using args.
   """
   url_file = urllib.urlopen(url)
   url_html = url_file.read()
 
   url_file.close()
 
   # Parses links with versions embedded.
   url_parser = HTMLDirectoryParser(regex=regex)
   url_parser.feed(url_html)
-  return reduce(_GreaterVersion, url_parser.link_list)
+  try:
+    return reduce(_GreaterVersion, url_parser.link_list)
+  except TypeError:
+    raise CrosImageDoesNotExistError('No image found at %s' % url)
 
 
 def GetNewestLinkFromZipBase(board, channel, zip_server_base):
   """Returns the url to the newest image from the zip server.
 
   Args:
     board: board for the image zip.
     channel: channel for the image zip.
     zip_server_base:  base url for zipped images.
+  Raises:
+    CrosImageDoesNotExistError if no image found using args.
   """
   zip_base = os.path.join(zip_server_base, channel, board)
   latest_version = GetLatestLinkFromPage(zip_base, '\d+\.\d+\.\d+\.\d+/')
 
   zip_dir = os.path.join(zip_base, latest_version)
   zip_name = GetLatestLinkFromPage(zip_dir,
                                    'ChromeOS-\d+\.\d+\.\d+\.\d+-.*\.zip')
   return os.path.join(zip_dir, zip_name)
 
 
 def GetLatestZipUrl(board, channel, zip_server_base):
   """Returns the url of the latest image zip for the given arguments.
 
-  If the latest does not exist, tries to find the rc equivalent.
+  If the latest does not exist, tries to find the rc equivalent.  If neither
+  exist, returns None.
 
   Args:
     board: board for the image zip.
     channel: channel for the image zip.
     zip_server_base:  base url for zipped images.
   """
   try:
     return GetNewestLinkFromZipBase(board, channel, zip_server_base)
-  except:
-    cros_lib.Warning('Failed to get url from standard zip base.  Trying rc.')
+  except CrosImageDoesNotExistError as ce:
+    cros_lib.Warning(str(ce))
+  try:
     return GetNewestLinkFromZipBase(board + '-rc', channel, zip_server_base)
+  except CrosImageDoesNotExistError as ce:
+    cros_lib.Warning(str(ce))
+    return None
 
 
 def GrabZipAndExtractImage(zip_url, download_folder, image_name) :
   """Downloads the zip and extracts the given image.
 
   Doesn't re-download if matching version found already in download folder.
   Args:
     zip_url - url for the image.
     download_folder - download folder to store zip file and extracted images.
     image_name - name of the image to extract from the zip file.
@@ skipping 67 matching lines @@
     board: the board for the latest image.
     channel: the channel to run the au test harness against.
     zip_server_base:  base url for zipped images.
     no_graphics: boolean - If True, disable graphics during vm test.
     type: which test harness to run.  Possible values: real, vm.
     remote: ip address for real test harness run.
     clean: Clean the state of test harness before running.
     test_results_root: Root directory to store au_test_harness results.
   """
   crosutils_root = os.path.join(constants.SOURCE_ROOT, 'src', 'scripts')
+
+  # Grab the latest image we've built.
+  return_object = cros_lib.RunCommand(
+    ['./get_latest_image.sh', '--board=%s' % board], cwd=crosutils_root,
+    redirect_stdout=True, print_cmd=True)
+
+  latest_image_dir = return_object.output.strip()
+  target_image = os.path.join(latest_image_dir, _IMAGE_TO_EXTRACT)
+
+  # Grab the latest official build for this board to use as the base image.
+  # If it doesn't exist, run the update test against itself.
   download_folder = os.path.abspath('latest_download')
   zip_url = GetLatestZipUrl(board, channel, zip_server_base)
-  GrabZipAndExtractImage(zip_url, download_folder, _IMAGE_TO_EXTRACT)
 
-  # Tests go here.
-  return_object = cros_lib.RunCommand(
-      ['./get_latest_image.sh', '--board=%s' % board], cwd=crosutils_root,
-      redirect_stdout=True, print_cmd=True)
-
-  latest_image = return_object.output.strip()
+  base_image = None
+  if zip_url:
+    GrabZipAndExtractImage(zip_url, download_folder, _IMAGE_TO_EXTRACT)
+    base_image = os.path.join(download_folder, _IMAGE_TO_EXTRACT)
+  else:
+    base_image = target_image
 
   update_engine_path = os.path.join(crosutils_root, '..', 'platform',
                                     'update_engine')
 
   private_key_path = os.path.join(update_engine_path, 'unittest_key.pem')
   public_key_path = GeneratePublicKey(private_key_path)
 
   cmd = ['bin/cros_au_test_harness',
-         '--base_image=%s' % os.path.join(download_folder,
-                                          _IMAGE_TO_EXTRACT),
-         '--target_image=%s' % os.path.join(latest_image,
-                                            _IMAGE_TO_EXTRACT),
+         '--base_image=%s' % base_image,
+         '--target_image=%s' % target_image,
          '--board=%s' % board,
          '--type=%s' % type,
          '--remote=%s' % remote,
          '--private_key=%s' % private_key_path,
          '--public_key=%s' % public_key_path,
          ]
   if test_results_root: cmd.append('--test_results_root=%s' % test_results_root)
   if no_graphics: cmd.append('--no_graphics')
   if clean: cmd.append('--clean')
 
@@ skipping 30 matching lines @@
   if not options.zipbase: parser.error('Need zip url base to get images.')
 
   RunAUTestHarness(options.board, options.channel, options.zipbase,
                    options.no_graphics, options.type, options.remote,
                    not options.cache, options.test_results_root)
 
 
 if __name__ == '__main__':
   main()