title: Cannot send session cookie - headers already sent PHPUnit / Laravel
body: <p>I have this strange problem when i call the <code>parent::setUp()</code> on my TestCase class for unit test a class
  when i run phpunit it throw me this error:</p>
  
  <blockquote>
    <p>1) MatchRequestRepositoryTest::test_find_requests_by_match_id
    ErrorException: session_start(): Cannot send session cookie - headers
    already sent by (output started at
    /var/www/project.dev/vendor/phpunit/phpunit/PHPUnit/TextUI/TestRunner.php:459)</p>
  </blockquote>
  
  <p>What can be the problem? Thanks for any help.</p>