public class XmlUtilTest extends PlainTestCase {

    public void test_escapeXml_null() {
        // Test null input
        assertEquals(StringUtil.EMPTY, XmlUtil.escapeXml(null));
    }

    public void test_escapeXml_empty() {
        // Test empty string
        assertEquals("", XmlUtil.escapeXml(""));
    }

    public void test_escapeXml_basic() {
        // Test basic XML escaping