How to use the restify-clients.createJsonClient function in restify-clients

// jscs:disable maximumLineLength

'use strict';

var chai = require('chai');
var _ = require('lodash');
var restify = require('restify-clients');
var demoServer = require('../example/demo');

var assert = chai.assert;
var client = restify.createJsonClient({
    url: 'http://localhost:3003'
});
var stringClient = restify.createStringClient({
    url: 'http://localhost:3003'
});

// star tests
describe('Integration tests using the demo app', function() {
    before(function(done) {
        demoServer.listen(3003, done);
    });

    after(function(done) {
        client.close();
        stringClient.close();
        demoServer.close(done);

function create(model) {
    assert.string(model.host, 'model.host');
    assert.optionalNumber(model.port, 'model.port');
    assert.optionalObject(model.headers, 'model.headers');

    var remoteHost = new Urijs(model.host)
        .port(model.port || 80)
        .protocol(model.secure ? 'https' : 'http')
        .toString();

    return restify.createJsonClient({
        url: remoteHost,
        // TODO: this doesn't seem to log anything?!
        log: logHelpers.child({ component: 'jsonClient' })
    });
}

it('should not accept unsupported content encoding', function (done) {
            SERVER.use(restify.plugins.bodyParser());

            CLIENT = restifyClients.createJsonClient({
                url: 'http://127.0.0.1:' + PORT,
                retry: false,
                headers: {
                    'content-encoding': 'unsupported'
                }
            });

            SERVER.post('/compressed', function (req, res, next) {
                assert.equal(req.body.apple, 'red');
                res.send();
                next();
            });

            CLIENT.post('/compressed', {
                apple: 'red'
            }, function (err, _, res) {

SERVER.listen(0, '127.0.0.1', function () {
                PORT = SERVER.address().port;
                CLIENT = restifyClients.createJsonClient({
                    url: 'http://127.0.0.1:' + PORT,
                    dtrace: helper.dtrace,
                    retry: false
                });

                done();
            });
        });

function createClient() {
    client = restify.createJsonClient({
      url: 'http://localhost:3000',
      version: '*',
      headers: {
        connection: 'close'
      }
    });
  }

constructor(context) {
    this._context = context
    this._pivotalTrackerClient = clients.createJsonClient(common.globals.pivotalBaseUrl)
    const projectId = context.workspaceState.get(common.globals.projectID)
    this._baseApiPath = `${common.globals.pivotalApiPrefix}/projects/${projectId}`
    this._token = context.globalState.get(common.globals.APItoken)
  }

constructor(apiKey, apiSecret) {
    this._apiKey = apiKey
    this._apiSecret = apiSecret
    this.client = clients.createJsonClient({
      url: 'https://api.kucoin.com'
    })
    this.path_prefix = '/v1'
  }

function createClient() {
    client = restify.createJsonClient({
      url: 'http://localhost:3000',
      version: '*',
      headers: {
        connection: 'close'
      }
    });
  }

//previous state store
    if (self._config.trackState) {
        self._prevState = [];
    }

    //logger
    if (self._config.log !== undefined) {
        try {
            self._log =  self._config.log.child({'module': 'MMcontrol'});
        } catch (exception) {
            throw new TypeError('passed log is not a bunyan logger');
        }
    }

    //JSON client
    self.client = restify.createJsonClient({
        url: self._config.url,
        userAgent: self._config.userAgent
    });

    //EventEmitter
    EventEmitter.call(self);
}