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