模拟构造函数回调

我正在为一个使用 react-native-sound ,所以我想嘲笑 react-native-sound 使用手动模拟 __mocks__ 文件夹。下面是模拟类:

export default class Sound {
  _filename = null;
  _basePath = null;
  _duration = -1;
  _currentTime = 0;
  _volume = 1;
  _loaded = false;

  constructor(filename, basePath, callback) {
    this._filename = filename;
    this._basePath = basePath;
    this._duration = 500;
    this._loaded = true;

    callback();
  }

  static setCategory = (value, mixWithOthers) => {};
  static setMode = value => {};
  static setActive = value => {};

  isLoaded = () => { return this._loaded; };
  getDuration = () =>  { return this._duration; };
  getCurrentTime = callback => {
    callback(this._currentTime);
  };
  getVolume = () => { return this._volume; };
  setVolume = value => {
    this._volume = value;
  };
}

audioplayer类有一个带有卷的可选参数的加载方法,如下所示:

export default class AudioPlayer {
  loaded = false;
  load = (path: string, volume: number = 1) => {
    const that = this;
    return new Promise((resolve, reject) => {
      const sound = new Sound(path, "", error => {
        if (error) {
          reject(error);
        } else {
          sound.setVolume(volume); // <----- Fail here
          loaded = true;
          resolve();
        }
      });
    });
  };

下面是我在单元测试中的尝试:

jest.mock("react-native-sound");

describe("audio-player", () => {
  it("can load audio file", () => {
    expect.assertions(1);
    const audioPlayer = new AudioPlayer();
    const path = "sample_audio.mp3";
    return audioPlayer.load(path).then(() => {
      expect(audioPlayer.loaded).toEqual(true);
    });
  });
});

但是,此操作失败,并显示以下错误消息:

类型错误:无法读取未定义的“setvolume”属性

这是因为试图设置卷的代码在构造函数中,不管什么原因,模拟类在构造函数中仍然是未定义的。我该怎么做?如何使用回调函数生成构造函数?