How to use the mockdate.set function in mockdate

beforeEach(async function() {
    mockdate.set("2015-11-05");
    mailChecker = sinon.stub( mailReceiver.for_test_only.transporter,"sendMail")
      .callsFake(function(obj, doit) { return doit(null, {response: "t"}); })
    await testutil.clearDB();
    await userModule.createNewUser({OSMUser: "TheFive", access: "full"});
    await articleModule.createNewArticle({blog: "blog", collection: "test"});
    testutil.startServerSync();
    browser = await testutil.getNewBrowser("TheFive");
    browser.evaluate(fs.readFileSync("./node_modules/timemachine/timemachine.js","UTF8"));
  });
  afterEach(function(bddone) {

beforeEach(() => {
    mockDate.set(1514764800000, 0);
  });

before(() => {
    MockDate.set(new Date());
    dateModified = getFormattedDateTime();
  });
  after(() => MockDate.reset());

beforeEach(() => {
    mockDate.set(1514764800000, 0);
  });

test.before(() => {
  mockery.enable({
    warnOnReplace: false,
    warnOnUnregistered: false,
    useCleanCache: true
  })
  mockdate.set(new Date(1427749200000))
})

it('should fail if startTime is previous than current time', () => {
    const values = {
      tiers: [
        {
          startTime: TIMESTAMPS.CURRENT_TIME,
          endTime: TIMESTAMPS.PLUS_5_MINUTES,
        },
        {
          startTime: TIMESTAMPS.PLUS_5_MINUTES,
          endTime: TIMESTAMPS.PLUS_10_DAYS,
        },
      ]
    }

    MockDate.set(TIMESTAMPS.PLUS_5_MINUTES)

    const validationResult = validateTierStartDate(0)(values.tiers[0].startTime, values)

    expect(validationResult).toEqual([VALIDATION_MESSAGES.DATE_IN_FUTURE])
  })

it('Should discard past ticks already closed', () => {
    MockDate.set('2018-03-13T12:00:00')

    tiers.forEach(tier => crowdsalePageStore.addTier(tier))
    expect(crowdsalePageStore.ticks.length).toBe(4)

    const activeTicks = ticks.slice(2)
    crowdsalePageStore.ticks.forEach((tick, index) => {
      expect(tick.type).toBe(activeTicks[index].type)
      expect(tick.time).toBe(activeTicks[index].time)
      expect(tick.order).toBe(activeTicks[index].order)
    })
  })

it("should consume an expired identity token", function () {
      factory.buildStub.returns(collection);

      MockDate.set(0);

      const token = "TOKEN";
      const challenge = "CHALLENGE";

      collection.findOneStub.withArgs().returns(BluebirdPromise.resolve({
        userId: "USER",
        token: token,
        challenge: challenge,
        maxDate: new Date()
      }));

      const dataStore = new UserDataStore(factory);

      MockDate.set(80000);

      return dataStore.consumeIdentityValidationToken(token, challenge)

it("should consume an identity token successfully", function () {
      factory.buildStub.returns(collection);

      MockDate.set(100);

      const token = "TOKEN";
      const challenge = "CHALLENGE";

      collection.findOneStub.withArgs().returns(BluebirdPromise.resolve({
        userId: "USER",
        token: token,
        challenge: challenge,
        maxDate: new Date()
      }));
      collection.removeStub.returns(BluebirdPromise.resolve());

      const dataStore = new UserDataStore(factory);

      MockDate.set(80);

before(() => {
    MockDate.set(new Date());
    dateModified = dateHelper.getFormattedDateTime();
  });
  after(() => MockDate.reset());