Not able to run phpunit test

I am using Drupal 8.2.6 and trying to run phpunit tests. I have successfully installed phpunit 4.1.* using composer. But when I am trying to run: cd core phpunit –testsuite=unit I am getting following error: PHP Fatal error: Call to undefined method DrupalTestsComponentRenderPlainTextOutputTest::prophesize() in /var/www/html/drupal/core/tests/Drupal/Tests/Component/Render/PlainTextOutputTest.php[…]