@Test public void singletonTest() { // create singleton instances final Singleton singleton1 = Singleton.getInstance(); final Singleton singleton2 = Singleton.getInstance(); final Singleton singleton3 = Singleton.getInstance(); // assert that the random number is the same thereby // ensuring we are dealing with a single object instance final int rand = singleton1.getRand(); assertEquals(rand, singleton2.getRand()); assertEquals(rand, singleton3.getRand()); // set a string message on a singleton final String message = "Singleton2 message"; singleton2.setMessage(message); // read the string message from the singletons assertEquals(message, singleton1.getMessage()); assertEquals(message, singleton3.getMessage()); }