### Question:
WroServletContextListener implements ServletContextListener { public final void setManagerFactory(final WroManagerFactory managerFactory) { notNull(managerFactory); this.managerFactory = managerFactory; }  final void contextInitialized(final ServletContextEvent event); final void contextDestroyed(final ServletContextEvent servletContextEvent); final void setManagerFactory(final WroManagerFactory managerFactory); final void setConfiguration(final WroConfiguration configuration);  }### Answer:
@Test(expected = NullPointerException.class) public void cannotSetNullWroManager() { victim.setManagerFactory(null); }