Mocking global date

mockDate.ts

// source: https://github.com/facebook/jest/issues/2234

let timeNow;
const realDate = Date;

describe("Stubbed Date", () => {
  beforeAll(() => {
    timeNow = Date.now();
    const _GLOBAL: any = global;
    _GLOBAL.Date = class {
      public static now() {
        return timeNow;
      }

      constructor() {
        return timeNow;
      }

      public valueOf() {
        return timeNow;
      }
    };
  });

  afterAll(() => {
    global.Date = realDate;
  });

  it("provides constant timestamps", () => {
    const ts1 = Date.now();
    const ts2 = +new Date();
    expect(ts1).toEqual(ts2);
    expect(ts2).toEqual(timeNow);
  });
});