To pass values to other test cases in mocha

The following is my index.js file (test -> index.js)

var token;

 describe('POST login', () => {
    it('should return status 200',  (done) => {
    chai.request(app)
    .post('login')
    .send({
      "email":"***@mail.com",
      "password":"***"
      })
    .end((err , response) => {  
     if(err) 
        done(err);
        response.should.have.status(200);
        token = response.header.token;
        done();
    }); 
  });
});

module.exports.token = token

This is my report test file (test -> report.js)

let chai = require('chai');
let chaiHttp = require('chai-http');
let {app} = require('../test');
chai.use(chaiHttp);
chai.should();
const {token} = require('./index');

beforeEach(function (done) {
      setTimeout(function(){
        done();
      }, 5000);
  });

  describe('POST /report', () => {
    it('should return status 200',  (done) => {
        console.log("MyToken" +token);
         chai.request(app)
            .post('/report')
            .set({'token': token})
            .end((err , response) => {  
             if(err) done(err);
                response.should.have.status(200);
                response.body.should.be.a('object');
                done();
         }); 
    });
});

But in the log, I'm getting the MyToken value as undefined. My question is, how can I pass the values across multiple tests? In case if null or undefined, it should stop other tests from executing.