def METHOD_NAME(self):
    AttachmentFactory(_signal=self.signal, file__filename='blah.txt', file__data=b'blah', is_image=False)
    jpg_data_uris, att_filenames, user_emails, att_created_ats = \
        DataUriImageEncodeService.get_context_data_images(self.signal, 800)
    self.assertEqual(len(jpg_data_uris), 0)
    self.assertEqual(len(att_filenames), 0)
    self.assertEqual(len(user_emails), 0)
    self.assertEqual(len(att_created_ats), 0)