- name: Make sure we used SystemdStrategy...
  lineinfile:
    path: "{{ _hostname_file }}"
    line: crocodile.ansible.test.doesthiswork.net.example.com
  check_mode: true
  register: etc_hostname
  failed_when: etc_hostname is changed

- name: ...and not RedhatStrategy
  lineinfile:
    path: /etc/sysconfig/network
    line: HOSTNAME=crocodile.ansible.test.doesthiswork.net.example.com
  check_mode: true
  register: etc_sysconfig_network
  failed_when: etc_sysconfig_network is not changed