e.g. in tests/tasks/main.yml:

```
- hosts: controller[0]
  - tasks:
    - include neutron.yml
```

and in tests/tasks/neutron.yml:

```
- name: neutron has the default router
  shell: . /root/stackrc; neutron router-list | grep default

- name: neutron has the internal_subnet with gateway_ip
  shell: . /root/stackrc; neutron subnet-show internal | grep gateway | grep gateway_ip
  ...
```

but however you want to slice it is fine.