Remove redundant code paths

[MrMino]

We are now constrained on pip >= 21.2.4 (bcfd93c). This elliminates code paths that were there previously in order to cater to the older versions of Pip:

• PipSession is now only found in pip._internal._network.session.
• install_req_from_line is always used.
• search_packages_info now always gives us a generator that yields pip._internal.commands.show._PackageInfo objects (not dict).

[MrMino]

Removing the extraneous monkeypatching revealed an interesting failure. I believe this is not related to this change, but still results in a bug. Requires further investigation.

[adamtheturtle]

Nice work.

I'd be happy if you want to split this up into "currently working" (we can merge that now) and "requires investigation".

You may have seen that I removed some patching in #88. I think that overall we can remove a lot of it and have a much more useful test suite.

[MrMino]

Will do.

[MrMino]

Working subset has been merged within #95. The issue with this part boils down to how we treat paths. By converting all mocked paths to the absolute ones, the tests start passing, but there's still some missing coverage.

I think we should stop using relative paths completely and start using pathlib.Path everywhere.

[adamtheturtle]

Thanks for doing this work.

I think we should stop using relative paths completely and start using pathlib.Path everywhere.

Sounds fine to me.

By converting all mocked paths to the absolute ones, the tests start passing, but there's still some missing coverage.

Are you familiar with how to track down what that missing coverage is? If not, let me know and I'm happy to point you In the right direction.

[MrMino]

Are you familiar with how to track down what that missing coverage is? If not, let me know and I'm happy to point you In the right direction.

I am, it's just that I'm not sure if it is the step in the right direction. I think it could be sidestepped by some of the points from #97. There's a lot of code that could be simplified and made more testable by refactoring some of the code base.

I'll try some of that next week.

[adamtheturtle]

Thank you @MrMino !

Based on your remaining work here, and the prompts in #97, I made the tests modified here "integration tests" (no more monkeypatching!) in #114 , and then removed the unused code paths as you have done here in #115. I'll therefore close this PR.