This post is an excerpt from the topics covered by our DrupalCon Dublin training: Drupal 8 Development - Workflows and Tools.

At Nuvole we consider writing good tests as a fundamental part of development and, when it comes to testing a complex site, there is nothing better than extensive behavioral tests using Behat. The benefits of such a choice are quite obvious:

• Tests are very easy to write.
• Behat scenarios serve as a solid communication mean between business and developers.

As a site grows in complexity, however, the default step definitions provided by the excellent Behat Drupal Extension might not be specific enough and you will quickly find yourself adding custom step to your FeatureContext or creating custom Behat contexts, as advocated by all official documentation.

This is all fine except that your boilerplate test code might soon start to grow into a non-reusable, non-tested bunch of code.

Enter Nuvole's Behat Drupal Extension.

Nuvole's Behat Drupal Extension

Nuvole's Behat Drupal Extension is built on the shoulders of the popular Behat Drupal Extension and it focuses on step re-usability and testability by allowing developers to:

• Organize their code in services by providing a YAML service description file, pretty much like we all are used to do nowadays with Drupal 8.
• Override default Drupal Behat Extension services with their own.
• Benefit of many ready-to-use contexts that are provided by the extension out of the box.

Installation and setup

Install Nuvole's Behat Drupal Extension with Composer by running:

bash $ composer require nuvoleweb/drupal-behat

Setup the extension by following the Quick start section available on the original Behat Drupal Extension page, just use NuvoleWeb\Drupal\DrupalExtension instead of the native Drupal\DrupalExtension in your behat.yml as shown below:

"Service container"-aware Contexts

All contexts extending \NuvoleWeb\Drupal\DrupalExtension\Context\RawDrupalContext and \NuvoleWeb\Drupal\DrupalExtension\Context\RawMinkContext are provided with direct access to the current Behat service container. Developers can also define their own services by adding a YAML description file to their project and setting the services: parameter to point to its current location (as shown above).

The service description file can describe both custom services and override already defined services. For example, given a tests/my_services.yml containing:

Then all contexts extending \NW\D\DE\C\RawDrupalContext or \NW\D\DE\C\RawMinkContext will be able to access that service by just calling:

The your.own.namespace.hello_world service class itself can be easily tested using PHPUnit. Also, since Behat uses Symfony's Service Container you can list services your service depends on as arguments so to remove any hardcoded dependency, following Dependency Injection best practices.

Override existing services

Say that, while working on your Drupal 7 project, you have defined a step that publishes a node given its content type and title and you want to use the same exact step on your Drupal 8 project, something like:

The problem here is that the actual API calls to load and save a node differs between Drupal 7 and Drupal 8.

The solution is to override the default Drupal core services specifying your own classes in your tests/my_services.yml:

You'll then delegate the core-specific business logic to the new core classes allowing your custom step to be transparently run on both Drupal 7 and Drupal 8. Such a step would look like:

Ready to use contexts

The extension also provides some utility contexts that you can use right away in your tests. Below a quick overview of what's currently available:

We will share more steps in the future enriching the current contexts as well as providing new ones so keep an eye on the project repository!

Disclaimer

At the moment only Drupal 8 is supported but we will add Drupal 7 support ASAP (yes, it's as easy as providing missing Drupal 7 driver core methods and adding tests).