WPT importer: Fix addition of --cc arguments for test owners.

third_party/WebKit/Tools/Scripts/webkitpy/w3c/test_importer_unittest.py

 # Copyright 2016 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.
 
 import collections
 
 from webkitpy.common.checkout.git_mock import MockGit
 from webkitpy.common.host_mock import MockHost
 from webkitpy.common.system.executive_mock import MockExecutive
 from webkitpy.common.system.log_testing import LoggingTestCase
@@ skipping 165 matching lines @@
         self.assertEqual(importer.get_directory_owners(), {('someone@chromium.org',): ['external/wpt/foo']})
 
     def test_get_directory_owners_no_changed_files(self):
         host = MockHost()
         host.filesystem.write_text_file(
             '/mock-checkout/third_party/WebKit/LayoutTests/W3CImportExpectations',
             '## Owners: someone@chromium.org\n'
             '# external/wpt/foo [ Pass ]\n')
         importer = TestImporter(host)
         self.assertEqual(importer.get_directory_owners(), {})
+
+    def test_cc_part(self):
+        directory_owners = {
+            ('someone@chromium.org',): ['external/wpt/foo', 'external/wpt/bar'],
+            ('x@chromium.org', 'y@chromium.org'): ['external/wpt/baz'],
+        }
+        self.assertEqual(
+            TestImporter._cc_part(directory_owners),
+            ['--cc=someone@chromium.org', '--cc=x@chromium.org', '--cc=y@chromium.org'])