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
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
其他回答
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
在这里引用了一些其他的答案来解决一个用Typescript的项目。我像这样创建了一个LocalStorageMock:
export class LocalStorageMock {
private store = {}
clear() {
this.store = {}
}
getItem(key: string) {
return this.store[key] || null
}
setItem(key: string, value: string) {
this.store[key] = value
}
removeItem(key: string) {
delete this.store[key]
}
}
然后我创建了一个LocalStorageWrapper类,我使用它来访问应用程序中的所有本地存储,而不是直接访问全局本地存储变量。便于在包装器中为测试设置模拟。
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');
});
});
});
至少到目前为止,localStorage可以很容易地在你的笑话测试中被监视,例如:
const spyRemoveItem = jest.spyOn(window.localStorage, 'removeItem')
就是这样。你可以像以前一样使用你的间谍。
在我的例子中,我需要在检查localStorage值之前设置它。
我所做的就是
const data = { .......}
const setLocalStorageValue = (name: string, value: any) => {
localStorage.setItem(name, JSON.stringify(value))
}
describe('Check X class', () => {
setLocalStorageValue('Xname', data)
const xClass= new XClass()
console.log(xClass.initiate()) ; // it will work
})
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