def METHOD_NAME(self):
    set_module_args({
        'token': 'xoxa-123456789abcdef',
        'msg': 'test with ts'
    })
    with patch.object(slack, "fetch_url") as fetch_url_mock:
        mock_response = Mock()
        mock_response.read.return_value = '{"fake":"data"}'
        fetch_url_mock.return_value = (mock_response, {"status": 200})
        with self.assertRaises(AnsibleExitJson):
            self.module.main()
        self.assertTrue(fetch_url_mock.call_count, 1)
        self.assertEquals(fetch_url_mock.call_args[1]['url'], "https://slack.com/api/chat.postMessage")