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/**
* Manage the instance of a custom `window.localStorage`
*
* This only encapsulates the setup / teardown logic so that it can easily be
* reused with different implementations (i.e. a spy or a [fake][1])
*
* [1]: https://stackoverflow.com/a/41434763/1708147
*
* @param {() => any} fn Function that returns the object to use for localStorage
*/
const useLocalStorage = fn => {
const origLocalStorage = window.localStorage;
let currentLocalStorage;
Object.defineProperty(window, 'localStorage', {
get: () => currentLocalStorage,
});
beforeEach(() => {
currentLocalStorage = fn();
});
afterEach(() => {
currentLocalStorage = origLocalStorage;
});
};
/**
* Create an object with the localStorage interface but `jest.fn()` implementations.
*/
export const createLocalStorageSpy = () => ({
clear: jest.fn(),
getItem: jest.fn(),
setItem: jest.fn(),
removeItem: jest.fn(),
});
/**
* Before each test, overwrite `window.localStorage` with a spy implementation.
*/
export const useLocalStorageSpy = () => useLocalStorage(createLocalStorageSpy);
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