### Question:
InjectorHolder { public static PaxWicketInjector getInjector() { String applicationName = Application.get().getApplicationKey(); PaxWicketInjector injector = null; synchronized (instance.injectorMap) { injector = instance.injectorMap.get(applicationName); } if (injector == null) { throw new IllegalStateException(String.format("No Injector is set for application %s", Application.get().getApplicationKey())); } return injector; } private  InjectorHolder(); static PaxWicketInjector getInjector(); static void setInjector(String applicationName, PaxWicketInjector newInjector);  }### Answer:
@Test(expected = IllegalStateException.class) public void testRetrieveNonExistingInjectionHolder_shouldThrowIllegalStateException() throws Exception { new WicketTester(); InjectorHolder.getInjector(); }