@Test
    public void test_roleConstants() {
        assertEquals("user", ChatMessage.ROLE_USER);
        assertEquals("assistant", ChatMessage.ROLE_ASSISTANT);
    }

    @Test
    public void test_chatSourceDefaultConstructor() {
        final ChatSource source = new ChatSource();
        assertEquals(0, source.getIndex());
        assertNull(source.getTitle());
        assertNull(source.getUrl());