Finally I manage to run sucesfully tests on GitLab. Here is the project: https://gitlab.com/gandra404/ticketbeast
This article helped me a lot: https://woohuiren.me/blog/how-to-laravel-testing-on-gitlab-ci-with-docker/
I have code on GitLab. Runner installed on my host(probably would work only with shared runner?) with docker as executor.
I have copied this files in my root: https://github.com/GIANTCRAB/gitlabby-dockerish-laravel
The only error I had at first try was "Unable to prepare route [api/user] for serialization. Uses Closure."(https://gitlab.com/gandra404/ticketbeast/builds/8359637) but seems that is known error: https://laracasts.com/discuss/channels/laravel/why-unable-to-prepare-route-for-serialization-uses-closure
So, at the moment I have commented line
php artisan route:cache andbuild paased ok!