final String uaid = UUIDUtil.newUAID();
final String channelId1 = UUID.randomUUID().toString();
final String channelId2 = UUID.randomUUID().toString();
sendWebSocketHttpUpgradeRequest(sessionUrl, channel);
sendWebSocketHelloFrame(uaid, channel);
final RegisterResponse registerResponse1 = sendWebSocketRegisterFrame(channelId1, channel);
final String endpointToken1 = extractEndpointToken(registerResponse1.getPushEndpoint());
sendNotification(endpointToken1, 1L, simplePushServer);
final RegisterResponse registerResponse2 = sendWebSocketRegisterFrame(channelId2, channel);
final String endpointToken2 = extractEndpointToken(registerResponse2.getPushEndpoint());
sendNotification(endpointToken2, 1L, simplePushServer);
final Set<Ack> unacked = sendAcknowledge(channel, ack(channelId1, 1L));
assertThat(unacked.size(), is(1));
assertThat(unacked, hasItem(new AckImpl(channelId2, 1L)));