ansible/test/integration/targets/reboot/tasks/test_invalid_test_command.yml

- name: Reboot with test command that fails
  reboot:
    test_command: 'FAIL'
    reboot_timeout: "{{ timeout }}"
  register: reboot_fail_test
  failed_when: "reboot_fail_test.msg != 'Timed out waiting for post-reboot test command (timeout=' ~ timeout ~ ')'"
  vars:
    timeout: "{{ _timeout_value[ansible_facts['distribution'] | lower] | default(60) }}"