// ========== escapeHtml tests ==========

    @Test
    public void test_escapeHtml_null() {
        assertEquals("", chatClient.testEscapeHtml(null));
    }

    @Test
    public void test_escapeHtml_empty() {
        assertEquals("", chatClient.testEscapeHtml(""));
    }

    @Test
    public void test_escapeHtml_noSpecialChars() {
        assertEquals("hello world", chatClient.testEscapeHtml("hello world"));