MockSMailPostingDiscloser discloser = new MockSMailPostingDiscloser();
        discloser.setSubject("Test Subject");
        discloser.setPlainText("Test Content");

        String result = notificationHelper.toSlackMessage(discloser);

        assertNotNull(result);
        assertTrue(result.contains("Test Subject"));
        assertTrue(result.contains("Test Content"));
        assertTrue(result.startsWith("{\"text\":\""));