Running tests without Drupal installed

With Drupal 8, tests can also be run from SQLlite and no longer requires an installed database. This can be accomplished by passing the sqlite and dburl options to the
run-tests.sh script. This requires the PHP SQLite extension to be installed.

Here is an example adapted from the DrupalCI test runner for Drupal core. DrupalCI is the continuous integration service, which runs on Drupal.org for all submitted patches and commits:

php core/scripts/run-tests.sh --sqlite /tmp/.ht.sqlite --die-on-fail --dburl sqlite://tmp/.ht.sqlite --all
  

Combined with the built-in PHP web server for debugging, you can run test suites without a full-fledged environment.