public void test_add_multipleEngines() {
        TestScriptEngine engine1 = new TestScriptEngine("engine1");
        TestScriptEngine engine2 = new TestScriptEngine("engine2");
        CustomScriptEngine customEngine = new CustomScriptEngine();

        scriptEngineFactory.add("engine1", engine1);
        scriptEngineFactory.add("engine2", engine2);
        scriptEngineFactory.add("custom", customEngine);