Test that a JWT is expired or expires within a certain window using Sinon's Fake Timers

jwtUtils-spec.js

import expect from "expect";
import sinon from "sinon";

// Inline version of function to be tested
const expiredOrExpiresWithin = (decodedJwt, seconds) =>
  Date.now() >= (decodedJwt.exp + (-Math.abs(seconds) || 0)) * 1000;

describe("jwtUtils", () => {
  describe("expiredOrExpiresWithin", () => {
    let clock;
    let decodedJwt;
    beforeEach(() => {
      clock = sinon.useFakeTimers(new Date(2018, 7, 29).getTime()); // sets date to Aug 29, 2018 at 00:00 UTC
      decodedJwt = {
        data: "foobar",
        iat: 1535566191,
        exp: 1535566197, // Wed Aug 29 2018 18:09:57 GMT+0000 (UTC)
      };
      /* const d = new Date(0); */
      /* d.setUTCSeconds(decodedJwt.exp); */
      /* console.log("JWT Date", d); */
    });
    afterEach(() => {
      clock.restore();
    });

    it("should be expired if jwt exp is in the past", () => {
      clock.tick(60 * 60 * 19 * 1000); // move the fake time ahead to 19:00:00
      /* console.log("Now Date", new Date()); */

      expect(expiredOrExpiresWithin(decodedJwt, 0)).toBe(true);
    });

    it("should NOT be expired if jwt exp is in the future", () => {
      /* console.log("Now Date", new Date()); */

      expect(expiredOrExpiresWithin(decodedJwt, 0)).toBe(false);
    });

    it("should be expired if jwt exp is in the future out of tolerance (1 minute - dev)", () => {
      clock.tick(60 * 60 * 18.16 * 1000); // move the fake time ahead to 18:09:36
      /* console.log("Now Date", new Date()); */

      expect(expiredOrExpiresWithin(decodedJwt, 60)).toBe(true);
    });

    it("should NOT be expired if jwt exp is in the future greater than tolerance", () => {
      /* console.log("Now Date", new Date()); */

      expect(expiredOrExpiresWithin(decodedJwt, 60)).toBe(false);
    });

    it("should be expired if jwt exp is in the future out of tolerance (1 hour - production)", () => {
      clock.tick(60 * 60 * 18.16 * 1000); // move the fake time ahead to 18:09:36
      /* console.log("Now Date", new Date()); */

      expect(expiredOrExpiresWithin(decodedJwt, 60 * 60)).toBe(true);
    });
  });
});