Run Drupal 8 web tests without installing Drupal

README.md

1. Create a MySQL database.
2. Create a user that has access to that database.
3. Make sure that you have the PDO_MySQL PHP library (otherwise you will get an error because it is missing).
4. Run the following script.
5. Once tests complete, we need to stop PHP's web server.

Note: there seem to be some issues with PHP's built-in web server. Please report them here https://www.drupal.org/node/1543858.

run_tests.sh

# Next, download core and run web tests.
wget -q -O -  http://ftp.drupal.org/files/projects/drupal-8.1.x-dev.tar.gz | tar xz
mv my_module drupal-8.1.x-dev/modules/
cd drupal-8.1.x-dev

# You need to download the module's dependencies. Perhaps Composer can do this?
drush dl ctools

# Start PHP's built-in web server in the background.
nohup php -S localhost:9000 > phpd.log 2>&1 &

# Run tests.
php ./core/scripts/run-tests.sh --sqlite /tmp/test.sqlite --dburl mysql://user:pass@localhost/db_name --url http://localhost:9000 --module my_module

Nice! Why do you need mysql at all if you're using --sqlite?

I think that there is still something in core that requires it. It is explained at https://www.drupal.org/node/645286#d8-no-install.