Canonical way to define page objects in Protractor

Question

We've been using the Page Object pattern for quite a while. It definitely helps to organize the end-to-end tests and makes tests more readable and clean.

As Using Page Objects to Organize Tests Protractor documentation page shows us, we are defining every page object as a function and use new to "instantiate" it:

"use strict";

var HeaderPage = function () {
    this.logo = element(by.css("div.navbar-header img"));
}

module.exports = HeaderPage;

Usage:

"use strict";

var HeaderPage = require("./../po/header.po.js");

describe("Header Look and Feel", function () {
    var header;

    beforeEach(function () {
        browser.get("/#login");
        header = new HeaderPage();
    });

    it("should show logo", function () {
        expect(header.logo.isDisplayed()).toBe(true);
    });

});

But, recently in the Protractor: Angular testing made easy Google Testing Blog post, I've noticed that a page object is defined as an object:

var angularHomepage = {
    nameInput : element(by.model('yourName')),
    greeting : element(by.binding('yourName')),
    get : function() {
        browser.get('index.html');
    },
    setName : function(name) {
        this.nameInput.sendKeys(name);
    }
};

What is the difference between these two ways to introduce Page Objects? Should I prefer one against the other?

Answer 1

Ultimately, I think it is a question of personal preference.

Yes, you can use the constructor pattern and instantiate a singleton in each test suite... yes you could use a simple object literal as above... yes you could use a factory function...

Structuring code using inheritance via "classes" (whether pseudo- or ES2015 syntax) vs objects extended via mixins is a much wider debate within application development in general, never mind e2e tests!

The main thing is clear, consistent practice across your test suites and promoting code reusability wherever possible.

Answer 2

Alecxe, I had this same question. The answer for me came down to the ability to extend constructor-based page objects. For things I don't need to extend (with a basePage, for example), I use an object literal.

This is just based on the things I've read and tried... I'd be happy to learn about a better/different pattern.

I look forward to reading the style guide, Andres.