    @Test
    void testEnvProperties() {

        Entry<String, String> entry = System.getenv().entrySet().iterator().next();
        String result = new Template("name", source, templatePattern, "${env@" + entry.getKey() + "}").
                resolveBy(resolver(), root).getContent();
        UnaryOperator<String> escape = v -> v.replaceAll("\\\\+", "/");
        assertEquals(escape.apply(entry.getValue()), escape.apply(result));
    }