Add does_storage_object_exist to gs_utils

py/utils/gs_utils_manualtest.py

 #!/usr/bin/python
 
 """Tests for gs_utils.py.
 
 TODO(epoger): How should we exercise these self-tests? See http://skbug.com/2751
 """
 
 # System-level imports.
 import os
 import posixpath
@@ skipping 370 matching lines @@
         file_contents = f.read()
       assert file_contents == 'contents of %s\n' % filename, (
           '%s == "contents of %s\n"' % (file_contents, filename))
   finally:
     shutil.rmtree(local_dest_dir)
     for filename in filenames:
       gs.delete_file(bucket=TEST_BUCKET,
                      path=posixpath.join(remote_dir, subdir, filename))
 
 
+def _test_does_storage_object_exist():
+  gs = gs_utils.GSUtils()
+  cases = (('gs_utils_manualtest/4843645167453050644/subdir/file1', True),
+           ('gs_utils_manualtest', True),
+           ('bogus', False))
+  for obj, expect in cases:
+    msg = 'expected exists(%s) to be %s' % (
+        '/'.join(('gs:/', TEST_BUCKET, obj)), expect)
+    assert gs.does_storage_object_exist(TEST_BUCKET, obj) == expect, msg
+
+
 if __name__ == '__main__':
   _test_static_methods()
   _test_upload_if_multiple_files()
   _test_upload_if_one_file()
   _test_public_read()
   _test_authenticated_round_trip()
   _test_dir_upload_and_download()
+  _test_does_storage_object_exist()
   # TODO(epoger): Add _test_unauthenticated_access() to make sure we raise
   # an exception when we try to access without needed credentials.