ansible/test/integration/targets/roles/allowed_dupes.yml

- name: test that import_role adds one (just one) execution of the role
  hosts: localhost
  gather_facts: false
  tags: ['importrole']
  roles:
     - name: a
  tasks:
    - name: import role ignores dupe rule
      import_role: name=a

- name: test that include_role adds one (just one) execution of the role
  hosts: localhost
  gather_facts: false
  tags: ['includerole']
  roles:
     - name: a
  tasks:
    - include_role: name=a