'Test the starting of a download when there are no new trackers'

def test_start_download_duplicate(self):

    mock_tdef = MockObject()
    mock_tdef.get_infohash = (lambda : ('a' * 20))
    mock_tdef.get_trackers_as_single_tuple = (lambda : tuple())
    mock_download = MockObject()
    mock_download.get_def = (lambda : mock_tdef)
    self.tribler_session.get_download = (lambda _: mock_download)
    self.ltmgr.tribler_session = self.tribler_session
    self.ltmgr.metadata_tmpdir = tempfile.mkdtemp(suffix=u'tribler_metainfo_tmpdir')
    self.assertRaises(DuplicateDownloadException, self.ltmgr.start_download, infohash=('a' * 20), tdef=mock_tdef)
