Mocha Unit Testing: Uncaught TypeError: Cannot read property 'apply' of undefined

I want to write unit testing for Restful Endpoint, but whenever I run npm test. I get the error Uncaught TypeError: Cannot read property 'apply' of undefined .

let chai = require('chai')
let chaiHttp = require('chai-http')
let home = require('../routes/home')
let user = require('../routes/users')
//Assertion Style
chai.should()

chai.use(chaiHttp)

describe('chow Api', () => {
  //  users
    describe("GET /api/chow/home", () => {
        it('it should render Welcome to Homepage', (done) =>{
            chai.request(home)
            .get("/api/chow/home")
            .end((err, response) =>{
                response.should.have.status(200)
                response.body.should.be('string')
                done()
            })
        })
    })

    describe('GET /api/chow/users', () => {
        it('it should GET all the users', (done) => {
            chai.request(user)
            .get("/api/chow/users")
            .end((err, response) =>{
                response.should.have.status(200)
                response.should.be.a('array')
                done()
            })
        })
    })
})