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