Node.js + mocha + selenium-webdriver

driver-provider.js

var SeleniumServer = require('selenium-webdriver/remote').SeleniumServer;
var webdriver = require('selenium-webdriver');
var promise = webdriver.promise;
var path = require('path');

var SELENIUM_SERVER_JAR = path.resolve(__dirname, 'selenium-server-standalone-2.45.0.jar');

function DriverProvider() {
	this._server = null;
	this._driver = null;
}

DriverProvider.prototype = {

	startServer: function () {
		this._server = new SeleniumServer(SELENIUM_SERVER_JAR, {port: 4444});
		return this._server.start();
	},

	stopServer: function () {
		return this._server.stop();
	},

	buildDriver: function () {
		this._driver = new webdriver.Builder()
			.usingServer(this._server.address())
			.forBrowser(webdriver.Browser.FIREFOX)
			.build();
		if (!this._driver) {
			throw new Error('Unable to build driver');
		}
		return promise.fulfilled(this._driver);
	},

	destroyDriver: function () {
		return this._driver ?
			this._driver.quit() :
			promise.rejected(new Error('No driver was found'));
	},

	getDriver: function () {
		return this._driver;
	},

	startUp: function () {
		var flow = promise.controlFlow();
		return promise.all([
			flow.execute(this.startServer.bind(this)),
			flow.execute(this.buildDriver.bind(this))
		]);
	},

	tearDown: function () {
		var flow = promise.controlFlow();
		return promise.all([
			flow.execute(this.destroyDriver.bind(this)),
			flow.execute(this.stopServer.bind(this))
		]);
	}

};

module.exports = exports = DriverProvider;

page-spec.js

var DriverProvider = require('./driver-provider');
var test = require('selenium-webdriver/testing');

test.describe('Page', function () {

	var driverProvider = new DriverProvider();

	test.before(function () {
		return driverProvider.startUp();
	});

	test.after(function () {
		return driverProvider.tearDown();
	});

	test.it('should be valid', function () {
		var driver = driverProvider.getDriver();
		// ...actual tests here
	});

});

@mekdev, sorry for my late reply.

I was wondering why we bind both startServer() and buildDriver()

These methods are binded to the DriverProvider instance. This instance can handle only one server and one driver instance. If you want to run 2 (or more) browser then you need more complicated logic in the buildDriver() and getDriver() methods.