fix: check for XDG_CACHE_HOME

[ShaiBlizzard]

Checklist

• Admin:
  • No duplicate PRs
• Integration:
  • Always add unit tests for fixes or new functionality

Description

Currently, if the user is using $XDG_CACHE_HOME which differs from $HOME/.cache, downgrade doesn't find anything
This makes it check both by default
(I've never worked with unit tests before so rather than mess up, set pr to draft)

[pbrisbin]

Nice fix, thanks.

This feels tricky (and low value) to unit test so I wouldn't worry about it. As long as it doesn't break current tests.

[pbrisbin]

This feels tricky (and low value) to unit test

Actually, that's not true.

Here is an existing test on this behavior:

downgrade/test/aur_fallback/detect_aur_caches.t

Lines 4 to 11 in 91395e6

	Detects yay cache when present
	$ fake_home=$(mktemp -d)
	> mkdir -p "$fake_home/.cache/yay"
	> get_real_user_home() { echo "$fake_home"; }
	> detect_aur_caches
	/tmp/*/yay (glob)
	[1]

I think it could be easy to add a case that runs with the XDG variable set and asserts that that takes precedence.

[ShaiBlizzard]

Got more familiar w the tests so whipped up this
Needed to also unset XDG else if the user had it defined, it caused most of the tests to fail (since it'd check that instead of checking fake_home)
Not sure if unsetting it at first should go here or in helper.sh

[ShaiBlizzard]

done
haven't exported an empty var before so dunno if the quotes are needed or not

[pbrisbin]

Thank you!