Using a Page Object

Intro

One of the biggest challenges with Selenium tests is that they can be brittle and challenging to maintain over time. This is largely due to the fact that things in the app you're testing change, breaking your tests.

But the reality of a software project is that change is a constant. So we need to account for this reality somehow in our test code in order to be successful.

A Solution

Enter Page Objects.

Rather than write your test code directly against your app, you can model the behavior of your application into simple objects -- and write your tests against them instead. That way when your app changes and your tests break, you only have to update your test code in one place to fix it.

And with this approach, we not only get the benefit of controlled chaos, we also get the benefit of reusable behavior.

Example

Let's take a test that works directly against a dynamic loading example found on the-internet. It clicks the start button, waits for the finish message to appear, and asserts that it says Hello World!. Every step uses the locators and the Selenium API directly.

We'll move all of that into a Page Object for the Dynamic Loading page:

The locators are pulled out into helpfully named constants (e.g., the start button and the finish text).
The constructor receives the Selenium WebDriver instance, visits the page, and verifies that we are in the right place.
Each test step becomes a method that describes the behavior of the page (e.g., start, wait for the finish message, and get the finish text).

With the Page Object in hand, the test becomes short and readable, and it no longer knows about locators.

It's worth noting that while we are performing an assertion in the Page Object when verifying the page, assertions should only be performed in your test scripts. Verifying the page on load is just a helpful exception to the rule.

Expected Behavior

Load the Dynamic Loading page on the-internet
Verify that we are on the right page
Click on start
Wait for the finish message to appear
Grab the text from it
Assert that it is the text we expect

Summary

Hopefully this tip has helped you wade into the waters of Page Objects in Selenium.

Stay tuned for a future tip where we implement a Base Page Object class to abstract things even further and roll our own Domain Specific Language (DSL) for our test suite.

Until then, Happy Testing!