How to run drush tests from the command line? I installed drush via composer, initially drush 8 was installed.

I then try to run tests via drush test-run command,unfortunately I get the following output indicating the command is not found. 


  (16:38 vagrant@devbox .composer) > drush test-run help The drush
  command 'test-run help' could not be found.  Run drush cache-clear
  drush to clear the       [error]


Installing version 7 via composer gives same output. Clearing the drush cache did not help, am I missing something?
The test-run command was removed from Drush; the recommendation now is to simply run the scripts/run-tests.sh script in Drupal folder directly.

See: Running tests through command-line.