在Jest测试中,我一直得到“localStorage is not defined”,这是有意义的,但我的选项是什么?碰壁。
当前回答
以下解决方案兼容更严格的TypeScript、ESLint、TSLint和Prettier配置测试:{"proseWrap": "always", "semi": false, "singleQuote": true, "trailingComma": "es5"}:
class LocalStorageMock {
public store: {
[key: string]: string
}
constructor() {
this.store = {}
}
public clear() {
this.store = {}
}
public getItem(key: string) {
return this.store[key] || undefined
}
public setItem(key: string, value: string) {
this.store[key] = value.toString()
}
public removeItem(key: string) {
delete this.store[key]
}
}
/* tslint:disable-next-line:no-any */
;(global as any).localStorage = new LocalStorageMock()
HT/ https://stackoverflow.com/a/51583401/101290了解如何更新global.localStorage
其他回答
这对我很有效,
delete global.localStorage;
global.localStorage = {
getItem: () =>
}
如果使用create-react-app,文档中解释了一个更简单和直接的解决方案。
创建src/setupTests.js,并把这个放在里面:
const localStorageMock = {
getItem: jest.fn(),
setItem: jest.fn(),
clear: jest.fn()
};
global.localStorage = localStorageMock;
Tom Mertz的评论如下:
然后,您可以通过执行以下操作来测试localStorageMock的函数是否被使用
expect(localStorage.getItem).toBeCalledWith('token')
// or
expect(localStorage.getItem.mock.calls.length).toBe(1)
在你的测试中,如果你想确保它被调用。查看https://facebook.github.io/jest/docs/en/mock-functions.html
或者你只是像这样使用一个模拟包:
https://www.npmjs.com/package/jest-localstorage-mock
它不仅处理存储功能,还允许您测试是否实际调用了存储。
不需要模拟localStorage—只需使用jsdom环境,这样您的测试就可以在类似浏览器的条件下运行。
在你的joke。config。js中,
module.exports = {
// ...
testEnvironment: "jsdom"
}
首先,我创建了一个名为localStorage.ts(localStorage.js)的文件
class LocalStorageMock {
store: Store;
length: number;
constructor() {
this.store = {};
this.length = 0;
}
key(n: number): any {
if (typeof n === 'undefined') {
throw new Error(
"Uncaught TypeError: Failed to execute 'key' on 'Storage': 1 argument required, but only 0 present."
);
}
if (n >= Object.keys(this.store).length) {
return null;
}
return Object.keys(this.store)[n];
}
getItem(key: string): Store | null {
if (!Object.keys(this.store).includes(key)) {
return null;
}
return this.store[key];
}
setItem(key: string, value: any): undefined {
if (typeof key === 'undefined' && typeof value === 'undefined') {
throw new Error(
"Uncaught TypeError: Failed to execute 'setItem' on 'Storage': 2 arguments required, but only 0 present."
);
}
if (typeof value === 'undefined') {
throw new Error(
"Uncaught TypeError: Failed to execute 'setItem' on 'Storage': 2 arguments required, but only 1 present."
);
}
if (!key) return undefined;
this.store[key] = value.toString() || '';
this.length = Object.keys(this.store).length;
return undefined;
}
removeItem(key: string): undefined {
if (typeof key === 'undefined') {
throw new Error(
"Uncaught TypeError: Failed to execute 'removeItem' on 'Storage': 1 argument required, but only 0 present."
);
}
delete this.store[key];
this.length = Object.keys(this.store).length;
return undefined;
}
clear(): undefined {
this.store = {};
this.length = 0;
return undefined;
}
}
export const getLocalStorageMock = (): any => {
return new LocalStorageMock();
};
global.localStorage = new LocalStorageMock();
然后创建名为session.test.ts的测试文件(session.test.js)
import { getLocalStorageMock } from '../localstorage';
describe('session storage', () => {
let localStorage;
beforeEach(() => {
localStorage = getLocalStorageMock();
});
describe('getItem', () => {
it('should return null if the item is undefined', () => {
expect(localStorage.getItem('item')).toBeNull();
});
it("should return '' instead of null", () => {
localStorage.setItem('item', '');
expect(localStorage.getItem('item')).toBe('');
});
it('should return navid', () => {
localStorage.setItem('item', 'navid');
expect(localStorage.getItem('item')).toBe('navid');
});
});
});