[IMPROVEMENT] Improve Asserts

[89luca89]

Some assertions should be improved, for example:

            host-vm-1:
              disk_source: "/mnt/iso/debian10-terraform.qcow2"
              os_family: Debian
              cpu: 1
              memory: 512
              hypervisor: hypervisor_1
              ansible_host: 192.168.122.9
              network_interfaces:
                iface_1:
                  name: default
                  type: nat
                  ip: 192.168.122.9
                  gw: 192.168.122.1
                  dns:
                    - 192.168.122.1
              default_route: True <<<--- note this is unindented

This snippets passes the assertions even if it's not valid
We should review and evaluate more corner cases to include in the assertions

Also we could think of an external tool/linter as @alegrey91 suggests to validate inventories

[alegrey91]

Yes, the idea is to create a classic linter such as ansible-lint, yamlint and so on to facilitate the inventory implementation.
We actually cannot base our inventory validation on the ansible-lint because Terrible has actually a lot of built-in that cannot be recognized e/o understood by the linter.

[89luca89]

Current asserts works on ansible while using python3 version of it we should make it clearer

[89luca89]

Yes, the idea is to create a classic linter such as ansible-lint, yamlint and so on to facilitate the inventory implementation.
We actually cannot base our inventory validation on the ansible-lint because Terrible has actually a lot of built-in that cannot be recognized e/o understood by the linter.

This should be part of #94