### Question:
PushResponder { static PushResponder getInstance() { if (INSTANCE == null) { throw new IllegalStateException("PushResponder is not initialized. " + "Please make sure to call PushResponder#init first."); } return INSTANCE; } private  PushResponder(StorageClient storageClient);   }### Answer:
@Test public void testShouldFailToGetInstanceNotInitialized() { PushResponder pushResponder = null; try { pushResponder = PushResponder.getInstance(); fail("Should throw IllegalStateException"); } catch (Exception e) { assertNull(pushResponder); assertTrue(e instanceof IllegalStateException); } }