Adding Functional (End-to-End) Test to Rookeries

Testing the client side of Rookeries, has proven to be quite a challenge. Not necessarily because testing well-written React JS components is hard. Rather I found it hard to setup a proper and consistent unit test infrastructure to do so. Rather than going through the pain of writing and maintaining functional tests in Javascript, I decided to take a different path.

BDD + Web Testing – Theory and Practise

I wanted to write my tests in a business-domain-driven (BDD) style. While most developers find awkward to use at first, it is a great way to write out the business functionality and features of an app. It also forces you to think about your app in a non-technical manner, and prove to yourself (and others) that it does what you claim it does.

At work my team has been burned by slow and awkward web tests. Namely we worked with the Robot Framework, which uses its own DSL and is very difficult to work just as we wanted. Debugging tests was also quite unpleasant.

Fortunately one of our newest team mates Kevin Qiu introduced us to lettuce (a BDD framework) and splinter (a Pythonic Selenium interface). And we’ve had a fair bit of success describing scenario using these tests. I won’t lie, Selenium is always temperamental. However the current batch of web tests have been very stable, and has very much convinced me that this setup can work effectively.

The Rookeries Take on BDD-style Web Testing

Rookeries usea a similar setup to what we’ve done at work: namely I use splinter to interface with Selenium. However unlike work, since Rookeries uses pytest instead of nose, I ended up using pytest-bdd to provide the BDD framework for Rookeries. Furthermore, I am using the pytest integration for splinter, to provide some of the browser fixtures needed for the tests.

Feel free to check out the functional tests in Rookeries to see examples of the tests. I also highly recommend watching Dylan Lacey ‘s talk about using Splinter for web testing at PyCon Australia 2013.

A Few Wrinkles I Found So Far

  • Dylan suggests using names for inputs when working with web tests. Unfortunately the react-bootstrap components I rely don’t include support for names, something I plan on submitting a patch/pull request for.
  • One needs to run a localized server as part of the functional tests, which makes for a slightly complicated task setup. This is something I need to simplify.
  • I found using the element.text of a container React component works around the issues of text phrases being broken up over a few components.
  • Using ids is the simplest way to find elements, even thought that isn’t what a user would actually use to navigate the site.
  • ipdb does not work very well when debugging tests. Plain old pdb works wonders though. I am considering switching over to using pdb++