Description of possible test phases transitions and status, including behavior of timeouts

[clebergnu]

Is your feature request related to a problem? Please describe.
During its execution, a test will be in different phases. So far, these are the definitions of the phases within an avocado-instrumented test:

avocado/core/test.py:        self.__phase = "INIT"
...
avocado/core/test.py:                self.__phase = "SETUP"
avocado/core/test.py:                self.__phase = "TEST"
avocado/core/test.py:                self.__phase = "TEARDOWN"
avocado/core/test.py:        self.__phase = "FINISHED"

As it can be seen, there's no central place defining the possible phases, just some aid to the test itself so that it knows where it's currently at.

In preparation for supporting timeouts for individual phases, it's a good idea to understand where the transitions from phases can and how they happen. For instance, what happens if a timeout is hit during the SETUP phase? Will it transition to FINISHED or will it go to TEARDOWN first?

Describe the solution you'd like
There should a reference document showing the possible:

• Test phases
• Phase transitions
• Associated possible statuses for each phase (example, it should be impossible for a test under INIT to have a pass status?)
• Phases where a timeout is supported

Additional information
This issue is based on the discussions from https://gitlab.com/avocado-framework/dovetail/-/issues/14

[richtja]

Resolved in #6012