There are lots of testing helpers, that make it pretty easy to test database stuff, see https://laravel.com/docs/5.7/database-testing and in particular https://laravel.com/docs/5.7/database-testing#available-assertions
You'll need to ensure you have a full suite of migrations, factories and seeds though.
i.e. you should be able to run php artisan migrate:fresh --seed at will, to wipe you database, run all migrations and seed dummy data.