### Question:
RemitSyncExecutor implements Handler.Callback { public void postSync(int id) { handler.sendEmptyMessage(id); } RemitSyncExecutor(@NonNull RemitAgent agent);   RemitSyncExecutor(@NonNull RemitAgent agent, @Nullable Handler handler,
                      @NonNull Set<Integer> freeToDBIdList); void postSyncInfoDelay(int id, long delayMillis); void postSync(int id); void postSync(List<Integer> idList); void postRemoveInfo(int id); void postRemoveFreeIds(List<Integer> idList); void postRemoveFreeId(int id); boolean handleMessage(Message msg);  }### Answer:
@Test public void postSync() { executor.postSync(1); verify(handler).sendEmptyMessage(eq(1)); executor.postSync(idList); verify(handler).sendMessage(messageCaptor.capture()); final Message message = messageCaptor.getValue(); assertThat(message.obj).isEqualTo(idList); assertThat(message.what).isEqualTo(WHAT_SYNC_BUNCH_ID); }