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
这对我很有效,
delete global.localStorage;
global.localStorage = {
getItem: () =>
}
其他回答
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
})
上面的答案对我都没用。经过一番挖掘,这就是我要做的。这要归功于一些来源和其他答案。
https://www.codeblocq.com/2021/01/Jest-Mock-Local-Storage/ https://github.com/facebook/jest/issues/6798#issuecomment-440988627 https://gist.github.com/mayank23/7b994385eb030f1efb7075c4f1f6ac4c https://github.com/facebook/jest/issues/6798#issuecomment-514266034
我的全部要点:https://gist.github.com/ar-to/01fa07f2c03e7c1b2cfe6b8c612d4c6b
/**
* Build Local Storage object
* @see https://www.codeblocq.com/2021/01/Jest-Mock-Local-Storage/ for source
* @see https://stackoverflow.com/a/32911774/9270352 for source
* @returns
*/
export const fakeLocalStorage = () => {
let store: { [key: string]: string } = {}
return {
getItem: function (key: string) {
return store[key] || null
},
setItem: function (key: string, value: string) {
store[key] = value.toString()
},
removeItem: function (key: string) {
delete store[key]
},
clear: function () {
store = {}
},
}
}
/**
* Mock window properties for testing
* @see https://gist.github.com/mayank23/7b994385eb030f1efb7075c4f1f6ac4c for source
* @see https://github.com/facebook/jest/issues/6798#issuecomment-514266034 for sample implementation
* @see https://developer.mozilla.org/en-US/docs/Web/API/Window#properties for window properties
* @param { string } property window property string but set to any due to some warnings
* @param { Object } value for property
*
* @example
*
* const testLS = {
* id: 5,
* name: 'My Test',
* }
* mockWindowProperty('localStorage', fakeLocalStorage())
* window.localStorage.setItem('currentPage', JSON.stringify(testLS))
*
*/
const mockWindowProperty = (property: string | any, value: any) => {
const { [property]: originalProperty } = window
delete window[property]
beforeAll(() => {
Object.defineProperty(window, property, {
configurable: true,
writable: true,
value,
})
})
afterAll(() => {
window[property] = originalProperty
})
}
export default mockWindowProperty
一个使用TypeScript和Jest的更优雅的解决方案。
interface Spies {
[key: string]: jest.SpyInstance
}
describe('→ Local storage', () => {
const spies: Spies = {}
beforeEach(() => {
['setItem', 'getItem', 'clear'].forEach((fn: string) => {
const mock = jest.fn(localStorage[fn])
spies[fn] = jest.spyOn(Storage.prototype, fn).mockImplementation(mock)
})
})
afterEach(() => {
Object.keys(spies).forEach((key: string) => spies[key].mockRestore())
})
test('→ setItem ...', async () => {
localStorage.setItem( 'foo', 'bar' )
expect(localStorage.getItem('foo')).toEqual('bar')
expect(spies.setItem).toHaveBeenCalledTimes(1)
})
})
在这个网站的帮助下,我们找到了答案:https://groups.google.com/forum/#!主题/ jestjs / 9 ephunwvytg
设置一个包含以下内容的文件:
var localStorageMock = (function() {
var store = {};
return {
getItem: function(key) {
return store[key];
},
setItem: function(key, value) {
store[key] = value.toString();
},
clear: function() {
store = {};
},
removeItem: function(key) {
delete store[key];
}
};
})();
Object.defineProperty(window, 'localStorage', { value: localStorageMock });
然后将以下行添加到包中。json在你的Jest配置
:“setupTestFrameworkScriptFile PATH_TO_YOUR_FILE”,
如果你正在寻找一个mock而不是存根,这是我使用的解决方案:
export const localStorageMock = {
getItem: jest.fn().mockImplementation(key => localStorageItems[key]),
setItem: jest.fn().mockImplementation((key, value) => {
localStorageItems[key] = value;
}),
clear: jest.fn().mockImplementation(() => {
localStorageItems = {};
}),
removeItem: jest.fn().mockImplementation((key) => {
localStorageItems[key] = undefined;
}),
};
export let localStorageItems = {}; // eslint-disable-line import/no-mutable-exports
为了便于初始化,我导出了存储项。例如,我可以很容易地将它设置为一个对象
在Jest + JSDom的新版本中,不可能设置这个,但是本地存储已经可用,你可以像这样监视它:
const setItemSpy = jest.spyOn(Object.getPrototypeOf(window.localStorage), 'setItem');
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