Page Objects

The page object pattern is a classic pattern to model application state (pages) and things you do (or an automated test tool does) to them.

There’s often negativity towards best practices, but I can confidently say that page objects are a best practice for test automation of UI systems, which isn’t saying they will be exactly the same in every context, but there’s a common best practice pattern there which you can use.

Page objects, as a pattern, typically:

  1. Inherit from a base page object/container which stores common actions like:
    • instantiating the object looking for a known element that defines that page’s existence
    • optionally allow a ‘visit’ to the page during instantiation using some defined URL/path
    • provides actions and properties common to all pages, for example: waiting for the page, checking the page is displayed, getting the title/url of the page, and checking cookies and local storage items for that page;
  2. Define actions as methods which are ways of interacting with that page (such as logging in);
  3. Do not expose internals about the page outside the page – for example they typically don’t expose elements or element selectors which should only be used within actions/methods for that page which are exposed; and
  4. Can also be modeled as components for user interfaces that are built using components to give greater re-usability of the same components across different pages.

The biggest benefit I have found from using page objects as a pattern is having more deterministic end-to-end tests since instantiating a page means you know you are on that page, so the automated tests will fail more reliably with a better understanding of what went wrong.

Further reading: