### Question:
RockerEngine extends TemplateEngine { @Override public String render(ModelAndView modelAndView) { return Rocker.template(modelAndView.getViewName()) .bind((Map<String,Object>)modelAndView.getModel()) .render() .toString(); }  @Override String render(ModelAndView modelAndView);  }### Answer:
@Test public void testRender() throws Exception { String templateVariable = "Hello Rocker!"; Map<String, Object> model = new HashMap<>(); model.put("message", templateVariable); String expected = String.format("<h1>%s</h1>\n", templateVariable); String actual = new RockerEngine().render(new ModelAndView(model, "views/hello.rocker.html")); assertEquals(expected, actual); }