Add empty default for test_data flag.

build/android/pylib/test_options_parser.py

 # Copyright (c) 2012 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.
 
 """Parses options for the instrumentation tests."""
 
 import constants
 import optparse
 import os
 import sys
@@ skipping 119 matching lines @@
                            dest='flakiness_dashboard_server',
                            help=('Address of the server that is hosting the '
                                  'Chrome for Android flakiness dashboard.'))
   option_parser.add_option('--buildbot-step-failure',
                            action='store_true',
                            help=('If present, will set the buildbot status '
                                  'as STEP_FAILURE, otherwise as STEP_WARNINGS '
                                  'when test(s) fail.'))
   option_parser.add_option('--disable_assertions', action='store_true',
                            help='Run with java assertions disabled.')
-  option_parser.add_option('--test_data', action='append',
+  option_parser.add_option('--test_data', action='append', default=[],
                            help=('Each instance defines a directory of test '
                                  'data that should be copied to the target(s) '
                                  'before running the tests. The argument '
                                  'should be of the form <target>:<source>, '
                                  '<target> is relative to the device data'
                                  'directory, and <source> is relative to the '
                                  'chromium build directory.'))
 
 def ValidateInstrumentationOptions(option_parser, options, args):
   """Validate options/arguments and populate options with defaults."""
@@ skipping 24 matching lines @@
                                          '%s.apk' % options.test_apk)
     options.test_apk_jar_path = os.path.join(
         _SDK_OUT_DIR, options.build_type, constants.SDK_BUILD_TEST_JAVALIB_DIR,
         '%s.jar' %  options.test_apk)
   if options.annotation_str:
     options.annotation = options.annotation_str.split()
   elif options.test_filter:
     options.annotation = []
   else:
     options.annotation = ['Smoke', 'SmallTest', 'MediumTest', 'LargeTest']