Local Behat Testing with Lando and Pantheon

If you've followed Pantheon's Build Tool Instructions and used Pantheon's Example Drops 8 Composer as the base to take advantage of CircleCI then you've encountered Behat tests. Behat tests are extremely valuable for testing site functionality before new code goes to production or a shared code stream. However, on a custom site these default tests provided by Pantheon are likely to fail if you've made even a benign change like deleting Tags vocabulary on a Drupal standard installation.

The first few times I encountered these tests and inevitable failures, I would summarily delete or comment out the Behat test and proceed with development as normal. "We'll come back to those later", I always said. One of the barriers to taking full advantage of the Behat scaffolding that Pantheon provided was that there wasn't obvious guidance on how to run the tests locally before they caused failures in CircleCI builds. 

However, with just a few file changes to your Lando-based project, you can have these tests running locally. Good test coverage can give developers confidence when pushing code and reduces the chance of breaking basic existing functionality. An investment in tests early in a project can save time and headaches later on and build confidence in the development team.

(These instructions assume Drops 8 2.3.1 composer-based installation.)

1. Add a drush alias file with url and db-url settings to drush/lando.aliases.drushrc.php.¹

    'https://epihc.lndo.site/',
     'db-url' => 'mysql://pantheon:pantheon@database:3306/pantheon',
   );

2. Add lando-specific behat config to tests/behat/behat-lando.yml.

   default:
     suites:
       default:
         contexts:
           - FeatureContext
           - Drupal\DrupalExtension\Context\DrupalContext
           - Drupal\DrupalExtension\Context\MinkContext
           - Drupal\DrupalExtension\Context\MessageContext
           - Drupal\DrupalExtension\Context\DrushContext
           - FailAid\Context\FailureContext
     extensions:
       Drupal\MinkExtension:
         goutte: ~
         base_url: https://epihc.lndo.site/  # Replace with your site's URL
       Drupal\DrupalExtension:
         blackbox: ~
         api_driver: 'drush'
         drush:
           alias: 'lando.epihc'

3. Add Behat tooling to the Lando config and restart/rebuild lando to .lando.yml.

   tooling:
     behat:
       description: Run behat tests.
       cmd:
         - appserver: /app/vendor/bin/behat --config=/app/tests/behat/behat-lando.yml

4. Run lando behat in terminal to run the tests.

The final task will be to update the Behat tests for your particular site's needs. Your main test file is at tests/behat/features/content.feature. Luckily Behat uses natural language and is pretty easy to write. 

Other things to know:

• Check out your dev dependencies for the packages that are working together to make the tests Drupal friendly. The Behat Drupal Extension page has some good references.
• We use Pantheon, Drops-8, and Lando as a starting point for many of our projects but other approaches are equally valid. 
• If you need to debug the actual build process on CircleCI, go to .ci/test/behat/run
• Behat tests aren't appropriate for every use case. Visual regression tests, linters, code sniffers, and/or unit test have their place as well. 

Hopefully these instructions will help you get started on your test-driven way!

¹ Replace pantheon with drupal8 when using the drupal8 Lando recipe. This database setting is required for Behat to run drush commands.