Jest mock cheet sheet

jest-mock-dates.md

dates

describe("mock global date", ()=> {
  beforeEach(async () => {
    global.Date.now = jest.fn(() => new Date("2020-01-01T12:00:00Z").getTime());
  });
  afterAll(() => {
    global.Date.now = RealDate;
  });
});

describe("mock date methods", ()=> {
  jest
    .spyOn(Date.prototype, "toISOString")
    .mockReturnValue("2020-01-01T12:00:00Z");
});

localStorage

jest.spyOn(Storage.prototype, "getItem").mockReturnValue("getItem");