prevayler.execute(new Soma());
Somador s = (Somador)prevayler.sistema();
assertEquals(5, s.total());
PrevaylerJr prevayler2 = createPrevayler();
Somador s2 = (Somador)prevayler2.sistema();
assertEquals(5, s2.total());
prevayler2.execute(new Soma());
assertEquals(10, s2.total());
prevayler2.execute(new Soma());
assertEquals(15, s2.total());
}