Update last tests for first version of test specification

[mattiaswal]

Description

Fix #606

Other information

Checklist

Tick relevant boxes, this PR is-a or has-a:

• [ ] Bugfix
  • [ ] Regression tests
  • [ ] ChangeLog updates (for next release)
• [ ] Feature
  • [ ] YANG model change => revision updated?
  • [ ] Regression tests added?
  • [ ] ChangeLog updates (for next release)
  • [ ] Documentation added?
• [ ] Code style update (formatting, renaming)
• [x] Refactoring (please detail in commit messages)
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[mattiaswal]

Nice work! I see now the container tests are really difficult to document, e.g., in comparison to DHCP client.

For the "test all possible interface combinations" test, @ahmkar94, me and wkz talked about how to describe networks that are internal to the DUT, like VETH pairs and bridges, that have no physical counterpart or connection to the host -- i.e., that we cannot describe in the topology.dot file. One option, that somehow was abandoned, was an ASCII art picture included in the top test docstring that would be translated to the Readme.adoc file. Maybe the container tests would benefit even more from this?

Example:

  .-------------.         .---------------.     .--------.
  |      |  tgt |---------| mgmt |        |     |  web-  |
  | host | data |---------| data | target |     | server |
  '-------------'         '---------------'     '--------'
                             |                    /
                            br0                  /
                              `----- veth0 -----'

Yes, it has been a struggle, An extra ASCII art I think will do it more understandable. But for now this will do, but of course you are right. We need do describe software-ports in a better way.