Subscriptions { public static Subscription empty() { return BooleanSubscription.create(); } private  Subscriptions(); static Subscription empty(); @Experimental static Subscription unsubscribed(); static Subscription create(final Action0 unsubscribe); static Subscription from(final Future<?> f); static CompositeSubscription from(Subscription... subscriptions);  }
@Test public void testEmpty() { Subscription empty = Subscriptions.empty(); assertFalse(empty.isUnsubscribed()); empty.unsubscribe(); assertTrue(empty.isUnsubscribed()); }