Fail gracefully when dm.json is not present

platform_tools/android/tradefed/upload_dm_results.py

 #!/usr/bin/env python
 # 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.
 
 """Upload DM output PNG files and JSON summary to Google Storage."""
 
 
 import datetime
 import os
@@ skipping 14 matching lines @@
   import gs_utils
 
   # Private, but Google-readable.
   ACL = gs_utils.GSUtils.PredefinedACL.PRIVATE
   FINE_ACLS = [(
     gs_utils.GSUtils.IdType.GROUP_BY_DOMAIN,
     'google.com',
     gs_utils.GSUtils.Permission.READ
   )]
 
+  if not os.path.isfile(os.path.join(dm_dir, 'dm.json')):
+    sys.exit("no dm.json file found in output directory.")
+
   # Move dm.json to its own directory to make uploading it easier.
   tmp = tempfile.mkdtemp()
   shutil.move(os.path.join(dm_dir, 'dm.json'),
               os.path.join(tmp,    'dm.json'))
 
   # Only images are left in dm_dir.  Upload any new ones.
   gs = gs_utils.GSUtils()
   gs.upload_dir_contents(dm_dir,
                          'skia-android-dm',
                          'dm-images-v1',
@@ skipping 20 matching lines @@
                          fine_grained_acl_list = FINE_ACLS)
 
 
   # Just for hygiene, put dm.json back.
   shutil.move(os.path.join(tmp,    'dm.json'),
               os.path.join(dm_dir, 'dm.json'))
   os.rmdir(tmp)
 
 if '__main__' == __name__:
   main(*sys.argv[1:])