bug/python pip argspec

[blast-hardcheese]

Why

When installing packages via pip by way of the Packages pane, we interpolate the CLI arg by way of arg + spec.

In looking for why this was the case, it turns out that we impose the same argument specifications on all languages, namely <pkg> <spec>, which gets confusing in situations like flask[async]>=2,<3, where the spec would actually be [async]>=2,<3.

Instead, we should defer to language specific parsing semantics where possible, accepting a wider variety of acceptable argspecs, which more closely resemble the args of the underlying commands, to be less confusing.

What changed

• Language-specific argument parsing overrides
• Sensible fallback of an empty version constraint to == instead of leaving it unconstrained
• For pip, maintain the users' version spec all the way through to writing back to requirements.txt, so upm add flask>=2.3.0 doesn't get turned into flask===2.3.3 on save.

Test plan

upm -l python3 --ignored-packages unit_tests --ignored-paths .pythonlibs add 'flask 2'  # Fails, expectedly, since `==2` is not a valid version of flask
upm -l python3 --ignored-packages unit_tests --ignored-paths .pythonlibs add 'flask 2.3.3'
upm -l python3 --ignored-packages unit_tests --ignored-paths .pythonlibs add 'flask'
upm -l python3 --ignored-packages unit_tests --ignored-paths .pythonlibs add 'flask==2.3.3'
upm -l python3 --ignored-packages unit_tests --ignored-paths .pythonlibs add -- 'flask[async]>=2,<3'

these all work as expected in both Poetry and Pip

[ryantm]

Changes look good. I'm a little concerned you didn't have to touch any tests when making them.

[blast-hardcheese]

I'm a little concerned you didn't have to touch any tests when making them.

Turns out we do not have tests around invoking upm add "$arg1" "$arg2" "$arg3". Good call.
I was looking in the wrong place. We do have tests that can be made to handle this case, though we don't have any tests that cover this specifically. I'll add.

[blast-hardcheese]

:woohoo: