[tests] unbloat tests/lora/utils.py

[sayakpaul]

What does this PR do?

We take the following approach:

• Use parameterized to combine similar flavored tests.
• Modularize repeated blocks of code into functions and use them as much as possible.
• Remove redundant tests.
• We make peft>=0.15.0 a mandate. So, I removed @require_peft_version_greater decorator.

In a follow-up PR, I will attempt to improve tests from the LoRA test suite that take the most amount of time.

[sayakpaul]

These are skipped appropriately from the parent method. I think it's okay in this case, because it eases things a bit.

[BenjaminBossan]

I haven't checked the PR yet, but I was wondering: When I do bigger refactors of tests, I always check the line coverage before and after the refactor and ensure that they're the same (in PEFT we use pytest-cov). IMO, having some kind of validation that the refactor maintains the same coverage (or increases it) is quite important, as it's hard to notice when suddenly, some lines of code are not tested anymore.

[sayakpaul]

Indeed, it's important. Do you have any more guidelines for me to do that?

[BenjaminBossan]

Do you have any more guidelines for me to do that?

So you can install pytest-cov if not already done and then add --cov=src/diffusers --cov-report=term-missing to your pytest invocation. Do this once for main and once for this branch. You get a report with something like this:

Name                                                  Stmts   Miss  Cover   Missing
-----------------------------------------------------------------------------------
src/peft/__init__.py                                     10      0   100%
src/peft/auto.py                                         71     34    52%   61, 82-142
src/peft/config.py                                      132     29    78%   39-43, 67, 89, 144, 148-172, 199-204, 225-228, 240, 242, 261-268, 344
src/peft/helpers.py                                      72     72     0%   15-251
src/peft/import_utils.py                                 94     56    40%   25, 30-35, 40-46, 54-73, 81, 87-98, 108, 128-147, 156-167, 172
src/peft/mapping.py                                      21     10    52%   25-26, 44, 65-78
src/peft/mapping_func.py                                 36     11    69%   73, 79, 85-89, 96, 103, 110, 123-125
[...]
src/peft/utils/peft_types.py                             58      6    90%   137, 140, 143, 156, 159, 163
-----------------------------------------------------------------------------------
TOTAL                                                 16679  12939    22%

It can be a bit difficult to parse what has changed, but basically, you want the missing column after the refactor to be 1) the same as before or 2) a subset (i.e. strictly better coverage). You could write a small tool to compare before and after (I know I did it once but can't find the snippet anymore) or just ask an LLM, they are quite good at finding the differences.