public void test_evaluate_stringOperations() {
        final Map<String, Object> params = new HashMap<>();
        params.put("first", "Hello");
        params.put("second", "World");

        assertEquals("HelloWorld", groovyEngine.evaluate("return first + second", params));
        assertEquals("HELLO", groovyEngine.evaluate("return first.toUpperCase()", params));
        assertEquals(5, groovyEngine.evaluate("return first.length()", params));