title: How to run phpunit tests on Symfony 4?
body: <p>When I try to run a functional test on Symfony 4, I get this:</p>
  
  <pre><code>The routing file "{__PATH__}config/routes/admin.yaml" contains unsupported keys for "admin_home": "controller". Expected one of: "resource", "type", "prefix", "path", "host", "schemes", "methods", "defaults", "requirements", "options", "condition", "ControllerTest"
  </code></pre>
  
  <p>I don't understand why because my routing configuration follows the official documentation:</p>
  
  <pre><code>admin_home:
      path: ''
      controller: App\Controller\Admin\HomeController::home
  </code></pre>
  
  <p>Official doc: <a href="http://symfony.com/doc/current/routing.html" rel="nofollow noreferrer">http://symfony.com/doc/current/routing.html</a> (in YAML tabs, I didn't install the annotations package). Where "controller" is a supported key.</p>
  
  <p>I installed the PHPUnit package <code>composer require --dev symfony/phpunit-bridge</code> then I run <code>./vendor/bin/simple-phpunit</code>.</p>