debian-mirror-gitlab/spec/frontend/helpers/local_storage_helper.js

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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;
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let currentLocalStorage = origLocalStorage;
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Object.defineProperty(window, 'localStorage', {
get: () => currentLocalStorage,
});
beforeEach(() => {
currentLocalStorage = fn();
});
afterEach(() => {
currentLocalStorage = origLocalStorage;
});
};
/**
* Create an object with the localStorage interface but `jest.fn()` implementations.
*/
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export const createLocalStorageSpy = () => {
let storage = {};
return {
clear: jest.fn(() => {
storage = {};
}),
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getItem: jest.fn(key => (key in storage ? storage[key] : null)),
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setItem: jest.fn((key, value) => {
storage[key] = value;
}),
removeItem: jest.fn(key => delete storage[key]),
};
};
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/**
* Before each test, overwrite `window.localStorage` with a spy implementation.
*/
export const useLocalStorageSpy = () => useLocalStorage(createLocalStorageSpy);