@Override
  public void loadData(Priority priority, DataCallback<? super T> callback) {
    this.callback = callback;
    serializer.startRequest(priority, url, this);
  }
@Test
  public void testRequestComplete_withNonNullException_callsCallbackWithException() {
    CronetException expected =
        new CronetException("test", /* cause= */ null) {
          static final long serialVersionUID = 1;
        };
    fetcher.loadData(Priority.LOW, callback);
    urlRequestListenerCaptor.getValue().onFailed(request, null, expected);

    verify(callback, timeout(1000)).onLoadFailed(eq(expected));
  }