Mocked response from file

readfromfile.js

var nock = require('nock');
var request = require('supertest')("http://api.postcodes.io");
var expect = require('chai').expect;
//used to read the JSON file
var fs = require("fs");

describe("Testing API with a mocked backend", function () {

  it("responds with json file response", function (done) {

    //read the json file
    var contents = fs.readFileSync('mockedresponse.json');
    //parse the contents and assign to a variable
    var jsonContent = JSON.parse(contents);

    nock("http://api.postcodes.io")
      .get('/postcodes/')
      .reply(200, jsonContent);

    request
      .get('/postcodes/')
      .expect(200)
      .end(function (err, res) {
        expect(res.body.status).to.equal(200);
        expect(res.body.result.postcode).to.equal("SW1A 1AA")
        done();
      });
  })
});