Question

我正在用Jest和Enzyme做本机反应的简单测试。目前，我正在测试和模拟AsyncStorage，但是每次测试都失败了。我尝试将代码放入beforeEach(() => {})内，但是它也不起作用。检查以下代码：

import 'react-native';
import React from 'react';
import configureStore from 'redux-mock-store';
import thunk from 'redux-thunk';
import MockStorage from '../../__mocks__/mockStorage';

const middlewares = [thunk]; 
const mockStore = configureStore(middlewares);

describe('testing AsyncStorage', () => {

    // Mock AsyncStorage
    const storageCache = {
        '@token': '123sometoken987',
        '@messages': 'this is a message'
    };

    const AsyncStorage = new MockStorage(storageCache);
    jest.setMock('AsyncStorage', AsyncStorage);
            ^ // fails here

    // ...
})

这是我的mockStorage.js：

export default class MockStorage {
    constructor(cache = {}) {
      this.storageCache = cache;
    }

    setItem = jest.fn((key, value) => {
      return new Promise((resolve, reject) => {
        return (typeof key !== 'string' || typeof value !== 'string')
            ? reject(new Error('key and value must be string'))
            : resolve(this.storageCache[key] = value);
         });
    });

    getItem = jest.fn((key) => {
      return new Promise((resolve) => {
        return this.storageCache.hasOwnProperty(key)
            ? resolve(this.storageCache[key])
            : resolve(null);
        });
    });

    removeItem = jest.fn((key) => {
      return new Promise((resolve, reject) => {
        return this.storageCache.hasOwnProperty(key)
            ? resolve(delete this.storageCache[key])
            : reject('No such key!');
        });
    });

    clear = jest.fn((key) => {
        return new Promise((resolve, reject) =>  resolve(this.storageCache = {}));
    });

    getAllKeys = jest.fn((key) => {
        return new Promise((resolve, reject) => resolve(Object.keys(this.storageCache)));
    });
  }

测试失败，并出现以下错误：

从'myFileName.js'中找不到模块'AsyncStorage'

有帮助吗？谢谢！

Answer 1

对于那些仍在寻找的人来说，这对我很有用。无法模拟整个react-native模块，但提供了AsyncStorage模块的路径。

const mockItems = {};
jest.mock('react-native/Libraries/Storage/AsyncStorage', () => ({
    setItem: jest.fn((item, value) => {
        return new Promise((resolve, reject) => {
            mockItems[item] = value;
            resolve(value);
        });
    }),
    getItem: jest.fn((item) => {
        return new Promise((resolve, reject) => {
            resolve(mockItems[item]);
        });
    }),
}));

Answer 2

您可以尝试在测试文件的beforeEach中设置模拟，而不是在根级别设置setMock

beforeEach(() => {
  const storageCache = {
    '@token': '123sometoken987',
    '@messages': 'this is a message'
  };

  jest.mock('AsyncStorage', () => new MockStorage(storageCache));
});

使用Jest / Enzyme测试时找不到模块“ AsyncStorage”

2 个答案: