title: PHPunit command not found after installing using composer
body: <p>I have added the PHPUnit dependency in the <code>composer.json</code>:</p>
  
  <pre><code>"require": {
    "php-ds/php-ds": "v1.2.0",
    "phpunit/phpunit": "v7.5.16"
  }
  </code></pre>
  
  <p>and ran composer update as I have <code>php-ds</code> installed already.</p>
  
  <p>This installed the PHPUnit in the vendor directory, but when I check <code>phpunit</code> in command line it says:</p>
  
  <blockquote>
    <p>phpunit command not found</p>
  </blockquote>