@Override
    public String toString() {
        return "{\"username\" : " + (_username == null ? null : "\"" + _username + "\"")
                + ",\"text\" : " + (_text == null ? null : "\"" + _text + "\"")
                + ",\"icon_emoji\" : " + (_iconEmoji == null ? null : "\"" + _iconEmoji + "\"")
                + ",\"channel\" : " + (_channel == null ? null : "\"" + _channel + "\"") + "}";
    }
@Test
    public void testSlackMessageJsonFormat() {
        String expectedJson = "{\"username\" : \"userA\",\"text\" : \"cc alert\",\"icon_emoji\" : \":information_source:"
                              + "\",\"channel\" : \"#cc-alerts\"}";
        assertEquals(expectedJson, new SlackMessage("userA", "cc alert", ":information_source:", "#cc-alerts").toString());
    }