Context (former Relevancy) implementation

[lukaszachy]

Let's start with examples for rules

[thrix]

Some examples from other fields, like versions from poetry (but it is related to packaging):

https://python-poetry.org/docs/versions/

Not applicable fully, but something could apply also to our use cases

[thrix]

library for parsing semver is here, but not sure if helps us :) https://github.com/python-poetry/semver

[lgtm-com]

This pull request introduces 3 alerts when merging 34b828b into 6570aa5 - view on LGTM.com

new alerts:

• 3 for Unused local variable

[coveralls]

Pull Request Test Coverage Report for Build 411

• 197 of 197 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 386:	0.0%
Covered Lines:	797
Relevant Lines:	797

---

💛 - Coveralls

[thrix]

@lukaszachy nice code man 👍

[lukaszachy]

@thrix thank you ;) and also for semver hint - I'll try to use it.
@psss I guess this could be used already, SUT() and SUT.matches() should be all you need to use from TMT.
Better name proposals welcome ;)

My plan for next days is to have 100% coverage and do docstrings + documentation.

After that I'll squash commits and resolve WIP

[psss]

Thanks for implementing this, @lukaszachy. I haven't reviewed the whole code but gave it a bit of testing and it works as expected. I was thinking a bit about the name and would like to propose Context instead of SUT. From the definition:

the circumstances that form the setting for an event, statement, or idea, and in terms of which it can be fully understood and assessed.

As we want to use not only environment dimensions but also things like trigger with values such as pull request, errata or compose to define in which context a test/plan is relevant, term context sounds general enough.

And second naming proposal: We were not sure about the rule attribute. I propose adjust which nicely describes what the rules are intended for: To adjust metadata based on rules. A simple example for illustration:

summary: Just a simple smoke test
test: tmt --help
enabled: true
adjust:
    enable: false
    when: distro = centos

What do you think?

[psss]

It seems that the following two unit tests fail:

TestExample.test_simple_conditions
TestExample.test_minor_comparisson_mode

[lukaszachy]

Worked on my system, I'll look at those flaky tests and will rename class

[psss]

Thanks. A couple of Python 2 compatiblity issues fixed in b703ce0. Feel free to squash them as well.

[lukaszachy]

Squashed previous commits, fixed tests. If tests pass then I'll rename the class and will ask for review.

[lukaszachy]

Todo

• nice docstring for (at least) public classes / methods
• chapter about Context to user-facing documentation (scope: motivation, rule grammar, intended usage)

[psss]

Thanks much for putting this together, @lukaszachy. That must have been a great patience and endurance exercise! Added a few comment and questions. Going to push a bunch of style adjustments in a separate commit as agreed.

[lukaszachy]

I expect a lot of changes for documentation, so it is in it's own PR: #86

From code/working PoV this PR is ready.

[psss]

Looks good. Thanks for the adjustments. Just two typos.

[psss]

Thanks, merged.