@Override
    public void init(Context context) {
      final SystemStreamPartition ssp =
          Iterables.getFirst(context.getTaskContext().getTaskModel().getSystemStreamPartitions(), null);
      if (ssp != null || ssp.getPartition().getPartitionId() == 0) {
        final int count =
            checkEachTask ? context.getContainerContext().getContainerModel().getTasks().keySet().size() : 1;
        LATCHES.put(id, new CountDownLatch(count));
        timer.schedule(timerTask, TIMEOUT);
      }
    }
Constructors a MessageStreamAssert with an id and serde
@param id unique id
@param messageStream represents messageStream that you want to assert on
@param serde serde used to desialize messageStream
@param <M> represents type of Message
@return MessageStreamAssert that returns the the messages in the stream
samza-test/src/main/java/org/apache/samza/test/framework/MessageStreamAssert.java