MessagerDebugBroadcast { boolean acceptSubscription(@NotNull MessagerDebugSubscription subscription) { if (!subscriptions.contains(subscription)) { subscriptions.add(subscription); return true; } else { return false; } }    }
@Test public void testAcceptSubscription() { assertTrue(broadcaster.acceptSubscription(subscriber)); assertTrue(broadcaster.hasSubscription(subscriber)); assertFalse(broadcaster.acceptSubscription(subscriber)); }