开玩笑模拟localStorage方法

Question

我想嘲笑localStorage方法以进行错误模拟。我在Utility.js中定义了localstorage
getter和setter方法。我想嘲笑localStorage.setItem在utility.setItem调用时抛出错误。

//file: utility.js
export default {
  getItem(key) {
    return localStorage.getItem(key);
  },
  setItem(key, value) {
    localStorage.setItem(key, value);
  }
};

开玩笑，

test('throw error', () => {
  localStorage.setItem = jest.fn(() => {
    console.log(" called ");
    throw new Error('ERROR');
  });

  utility.setItem('123', 'value');
});

但是localStorage.setItem模拟永远不会被调用。我也尝试过

window.localStorage.setItem = jest.genMockFunction(()=>{console.log(" Mock Called")});
global.localStorage.setItem = jest.fn(()=>{console.log(" Mock Called")});

Answer 1

这与Andreas在答案中建议的一致，但是我能够使用Storage接口对其进行模拟。我做了这样的事情

开玩笑，

test('throw error', () => {
  Storage.prototype.setItem = jest.fn(() => {
    console.log(" called "); // <-- was called 
    throw new Error('ERROR');
  });

  utility.setItem('123', 'value');
});

这次公关讨论也很有帮助。