jest-localstorage-mock/src/localstorage.js

Auto mock all localstorage and sessionstorage APIs for your Jest tests

export class LocalStorage {
  constructor(jest) {
    Object.defineProperty(this, 'getItem', {
      enumerable: false,
      value: jest.fn((key) => (this[key] !== undefined ? this[key] : null)),
    });
    Object.defineProperty(this, 'setItem', {
      enumerable: false,
      // not mentioned in the spec, but we must always coerce to a string
      value: jest.fn((key, val) => {
        this[key] = val + '';
      }),
    });
    Object.defineProperty(this, 'removeItem', {
      enumerable: false,
      value: jest.fn((key) => {
        delete this[key];
      }),
    });
    Object.defineProperty(this, 'clear', {
      enumerable: false,
      value: jest.fn(() => {
        Object.keys(this).map((key) => delete this[key]);
      }),
    });
    Object.defineProperty(this, 'toString', {
      enumerable: false,
      value: jest.fn(() => {
        return '[object Storage]';
      }),
    });
    Object.defineProperty(this, 'key', {
      enumerable: false,
      value: jest.fn((idx) => Object.keys(this)[idx] || null),
    });
  } // end constructor

  get length() {
    return Object.keys(this).length;
  }
  // for backwards compatibility
  get __STORE__() {
    return this;
  }
}