The very first time you need to pull the MariaDB docker image: docker pull mariadb
.
cd tests
phpunit
run xdebug with this configuration:
zend_extension=xdebug.so
xdebug.start_with_request = yes
xdebug.mode = debug
xdebug.client_port = 9000
xdebug.log = /var/log/xdebug.log