ManagerComponentImpl implements ManagerComponent { @Override public Stream<Manager<?>> stream() { return managersByEntity.values().stream(); } ManagerComponentImpl(); @Override void put(Manager<ENTITY> manager); @Override @SuppressWarnings("unchecked") Manager<E> managerOf(Class<E> entityClass); @Override Stream<Manager<?>> stream();  }
@Test void stream() { final Manager<String> manager = new MockStringManager(); instance.put(manager); assertEquals(1, instance.stream().count()); }