@Override
  public void loadData(Priority priority, DataCallback<? super T> callback) {
    this.callback = callback;
    serializer.startRequest(priority, url, this);
  }
@Test
  public void testRequestComplete_with200AndCancelled_callsCallbackWithNullException()
      throws Exception {
    UrlResponseInfo info = getInfo(0, 200);
    fetcher.loadData(Priority.LOW, callback);
    Callback urlCallback = urlRequestListenerCaptor.getValue();
    urlCallback.onResponseStarted(request, info);
    urlCallback.onCanceled(request, info);

    verify(callback, timeout(1000)).onLoadFailed(ArgumentMatchers.<Exception>isNull());
  }