init do
    `alter table comments add constraint users_fk foreign key(user_id) references users(id)`
    `insert into users(id) values (1)`
    `insert into comments(id, user_id) values (1, 1)`
    `delete from users where id = 1`
end

property eventually(`select count(*) from users` = 0 and `select count(*) from comments` = 0)