Merge python_version and python_full_version markers

[radoering]

Relates-to: python-poetry/poetry#5717

• Added tests for changed code.
• Updated documentation for changed code.

Reintroduces merging of python_version and python_full_version, which was removed in #382 because of python-poetry/poetry#5717

The constraint of the python_marker is converted via get_python_constraint_from_marker() and thus should be consistent with the latest findings described in #385.

[neersighted]

Given how brittle this has been I'm a little nervous about your change as I'm not quite familiar enough with the subtleties here -- however the set of test cases look quite robust and I can easily reason about that part of the change.

@dimbleby could you PTAL?

[dimbleby]

I think this looks correct, I'll leave a couple of style quibbles.

I continue to have a slight feeling of unease that this code has become so elaborate: I like a marker simplification as much as the next person, but there's so much of it!

[neersighted]

I think this looks correct, I'll leave a couple of style quibbles.

I continue to have a slight feeling of unease that this code has become so elaborate: I like a marker simplification as much as the next person, but there's so much of it!

I don't necessarily disagree, but I think ultimately we get higher quality results if we try to make sure the markers are as consistent and clean as possible. I think our best tool for maintainability is robust and through testing, and incremental refactoring as better patterns make themselves apparent. That being said, yes there's getting to be a lot of it and if I don't pay attention for a few weeks I forget how it works again 😆

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
1.2% Duplication

[radoering]

I continue to have a slight feeling of unease that this code has become so elaborate: I like a marker simplification as much as the next person, but there's so much of it!

It's just necessary for the solver to not try solving some bogus overrides. Solving not just for one environment is complex, but that's one of poetry's USPs.