MessagerDebugBroadcast { boolean cancelSubscription(@NotNull MessagerDebugSubscription subscription) { if (subscriptions.contains(subscription)) { subscriptions.remove(subscription); return true; } else { return false; } }    }
@Test public void testCancelSubscription() { assertFalse(broadcaster.cancelSubscription(subscriber)); assertTrue(broadcaster.acceptSubscription(subscriber)); assertTrue(broadcaster.cancelSubscription(subscriber)); }