Note: this is a long post!
Not long ago I wrote about functional tests and the page objects pattern in Aqris’ blog. Back then we at Aqris got all very excited about page objects as they were the solution we were looking for to solve our problems on maintaining our functional test code base, which by that time was based on a set of messy helpers that nobody really understood completely.
Before page objects, whenever a developer in our team had to write a test that had to perform an action no other test already performed, he or she would go through that bunch of helpers trying to figure out which one was the helper that should perform such an action. The result of this approach was that the team couldn’t get to a full agreement on what was each helper’s responsibilities. Everybody agreed that the code was not good, but each person had their point of view on why.
We first learned about the pattern here, when reading about WebDriver (now Selenium 2). Page objects came as the solution to separate the different actions our helpers contained in an extremely simple and even obvious way that nobody in our team had previously thought: simply creating a specialized helper for each page of the application.
It is in fact so simple that I still wonder how come we didn’t think of that before… I think that we were too busy trying to figure out how to deal with the helpers we had, and we were too used to have them that way. I guess that’s because the previous project we had worked on (and the first one we had a strong movement towards automated tests with Selenium) was a web app based on only one single page with lots of GWT-based ajax.
Anyway, excuses aside, we started using page objects and it was great! But then other doubts started to come up: how to deal with parts of a page that are common to many pages – for instance a side navigation bar? How to make our tests more readable? Should our page objects use selenium directly? If yes, how to resolve the selenium dependency? Can the page objects just encapsulate the locators for the html elements instead? Should page objects be responsible for the tests assertions too, depending on xUnit’s API, or should they just provide verification methods that would be used by our tests’ code itself?
I think that these are questions that may or may not have a straight correct answer, but here I will write a bit of what worked well for us or for me later on when dealing with that.
To do that I think we can write a test for an imagined scenario.
Let’s try that!
Let’s say that we have a test case to test the following hypothetical scenario:
We have a hypothetical book store application.
Every page in the application has a navigation bar on the side.
An user goes to our application home page and, by clicking on a link on the navigation bar, she goes to a page to search for books.
On the search books page she fills in a search form, entering “Tolkien” in the author field and “Rings” in the title field, and submits the form.
She is then redirected to a search result page that contains a list of books along with the same search form already filled in with the same search data she had entered – in this case, “Tolkien” in the author field and “Rings” in the title field.
We want to assure that, given our test data, the search result contains the book ‘The Return Of The King’.
We also want to assure that the search form in the result page still has the data she had previously entered.
The code solution after the jump :)