Fix #168: avoid creating duplicate link for addon

[Mateusz-Grzelinski]

In this PR:

• allow user to develop addon even it is placed in directories like (without creating duplicate addon link):
  • \4.2\scripts\addons -> default dir for addons
  • \4.2\extensions\blender_org -> directory indicated by bpy.context.preferences.extensions.repos (list of directories)
• use python3.7 syntax for compability
• ensured (basic) compability with blender 2.80
• remove duplicate links to development (VSCode) directory
• remove broken links in addon and extension dir

Squash merge when ready. Please squash merge after #174 - it fixes one more issue with 2.80 compability

About tests:

• they are mostly for me, just nice to have. if you look closesly they are missing many asserts and many errors will slip through when tesing on real blender instance.
• should be cross platform, but tested only on windows
• the tests run outside of blender. bpy and addon_utils are not necessary for tests
• how to run:

pip install pytest
cd pythonFile
$env:PYTHONPATH="./include" # powershell
pytest -s .\tests 

I could not figure out how to run tests with VS code UI. Works fine with pycharm UI when you mark include directory as source directory.

todo:

• fix tests

Corner cases (for documentation):

• junctions and hard links are difficult to manage
  • python behaves completely differently when touching junction in different python versions!
• link to extension is already present in different repository - remove the link
• link to addon is already present in addon directory but has different name - remove the link
• You are developing extension in addons directory (legacy addon not supported) - make a link
• You are developing addon in extensions directory (no extension support) - make a link
  • why would you do that to me...
• extension has legacy bl_info defined (supportes both legacy and new addon systems) - prefer extension for >4.2, otherwise addon
• extension has legacy bl_info defined (supportes both legacy and new addon systems) BUT user is developing addon in addon directory - treat as addon - do not make a link.

[Mateusz-Grzelinski]

The change should be working now.
I tried adding some basic tests, but I did something wrong, because

• if you run tests one by one they work
• if you run the whole file the tests fail - the patch bleeds into other functions. I have no idea how to fix it.

Note: I have basic experience with tests.

pip install pytest
cd pythonFile
$env:PYTHONPATH="./include" # powershell
pytest -s .\tests\blender_vscode\test_load_addons.py::TestIsInAnyAddonDirectory::test_is_in_any_addon_directory # ok
pytest -s .\tests  # 1 ok 5 fail

[Mateusz-Grzelinski]

I think I fixed the tests, but i need to sleep on it.

• rooky mistake: patch calls where they are made
• confusing patching behaviour: you can not patch the attributes in same path in two places (probably)
• removing modules works differently than I anticipated
• mocking global variables is hard
• fixed python 3.7 compability (blender 2.90)

Those tests are just prototypes that helped me find 2 more errors in my code. I am not sure if this is the right way to test (very complicated test for little code)

The tests are prepared to run outside of blender, and without fake-bpy-module

[Mateusz-Grzelinski]

• found even more issues (and fixed them)
• made a super-duper long test. The test is not that complicated but the patching is complicated.

Ehh, enother long evening.

[Mateusz-Grzelinski]

I am pretty sure this patch works as expected. Final test was done by adding addon and extension to both

• \4.2\scripts\addons
• \4.2\extensions\blender_org

as seen on screeshot, all looks ok.

The policy violation was fixed in 445778f

I verified that tests work even if fake-bpy-module is installed.

[JacquesLucke]

Would be good if you could update the initial PR description to be a bit more comprehensive.

A few words about how to run the tests would be good too. Also looks like they work on linux only (it's ok, but would be good to be more explicit about it)?

[Mateusz-Grzelinski]

ugh, breaks older blender. Totally forgot about that. I need to fight the persmission denied error when pip installing and check with blender 2.8 - i think this is the oldest one we support.

Hey, but I am developing this PR on windows, tests should work... Oh, I named the path in Linux style. It does not matter, it works on windows

[Mateusz-Grzelinski]

fixed compability with bledner 2.80. Please squash merge after #174 - it fixes one more issue with 2.80 compability

[Mateusz-Grzelinski]

there are problems with python 3.7 and dealing with junctions in windows. They are not recognized correctly and give different errors than python 3.12

[Mateusz-Grzelinski]

technically, there is no need to "panic" here, we can still load other addons, but there is no indication that linking failed and bledner needs to be restarted anyways...

[Mateusz-Grzelinski]

This became very involving change, hopefully this is last iteration and I will merge it on the weekend.
Before release Linux needs some testing.

[Mateusz-Grzelinski]

tested on ubuntu 22.04 snap installed blender 4.2. Works fine.
Merging.