Looks like newer browser DOMParser implemmentations parse differently

Author: jcbrand

tests/tests.js

@@ -443,7 +443,11 @@ test('XML serializing', function (assert) {
     const element9 = parser.parseFromString('<foo><![CDATA[<foo>]]></foo>', 'text/xml').documentElement;
     assert.equal(Strophe.serialize(element9), '<foo><![CDATA[<foo>]]></foo>', 'should be serialized');
     const element10 = parser.parseFromString('<foo><![CDATA[]]]]><![CDATA[>]]></foo>', 'text/xml').documentElement;
-    assert.equal(Strophe.serialize(element10), '<foo><![CDATA[]]]]><![CDATA[>]]></foo>', 'should be serialized');
+    if (globalThis.DOMParser) {
+        assert.equal(Strophe.serialize(element10), '<foo><![CDATA[]]>]]></foo>', 'should be serialized');
+    } else {
+        assert.equal(Strophe.serialize(element10), '<foo><![CDATA[]]]]><![CDATA[>]]></foo>', 'should be serialized');
+    }
     const element11 = parser.parseFromString('<foo>&lt;foo&gt;<![CDATA[<foo>]]></foo>', 'text/xml').documentElement;
     assert.equal(Strophe.serialize(element11), '<foo>&lt;foo&gt;<![CDATA[<foo>]]></foo>', 'should be serialized');
 });