### Question:
DashboardExtension extends DefaultController implements MonitorExtension { @Override public String category() { return "root"; } DashboardExtension(); @Validate void start(); @Route(method = HttpMethod.GET, uri = "/metrics") Result metrics(); @Route(method = HttpMethod.GET, uri = "/threads") Result threads(); @Invalidate void stop(); @Route(method = HttpMethod.GET, uri = "") Result index(); @Override String label(); @Override String url(); @Override String category();  }### Answer:
@Test public void testCategory() throws Exception { DashboardExtension extension = new DashboardExtension(); assertThat(extension.category()).isEqualTo("root"); }