ansible/test/integration/targets/dnf/tasks/dnfreleasever.yml

# make an installroot
- name: Create installroot
  command: mktemp -d "{{ remote_tmp_dir }}/ansible.test.XXXXXX"
  register: dnfroot

- name: Make a necessary directory
  file:
    path: "/{{dnfroot.stdout}}/etc/dnf/vars"
    state: directory
    mode: 0755

- name: Populate directory
  copy:
    content: "{{ansible_distribution_version}}\n"
    dest: "/{{dnfroot.stdout}}/etc/dnf/vars/releasever"

- name: attempt releasever to the installroot
  dnf:
    name: filesystem
    installroot: '/{{dnfroot.stdout}}'
    releasever: '{{ansible_distribution_version|int - 1}}'
  register: dnf_result

- name: check filesystem version
  shell: rpm -q filesystem --root="/{{dnfroot.stdout}}/"
  failed_when: False
  register: rpm_result

- debug: var=dnf_result
- debug: var=rpm_result

- name: verify installation was done
  assert:
    that:
      - "not dnf_result.failed | default(False)"
      - "dnf_result.changed"
      - "rpm_result.rc == 0"

- name: verify the version
  assert:
    that:
      - "rpm_result.stdout.find('fc' ~ (ansible_distribution_version|int - 1)) != -1"

- name: cleanup installroot
  file:
    path: "/{{dnfroot.stdout}}/"
    state: absent