[Tests] add test for checking soft dependencies.

[sayakpaul]

Fixes: #2356

Let me know if there's a better way to define the soft dependencies.

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[patrickvonplaten]

This test wouldn't catch if a user accidentally introduces a new dependency. Let's try to make two tests here:

1.) Simply check that from diffusers import * doesn't throw an error -> this should work and not throw an error. This is an important test still because it means we catch if incorrect "import ..." are added
So let's just test:

import diffusers

here

2.) Next, we import all classes of diffusers and make sure that in case those are dummy classes that they required backend is part of the dependencies. You can do the following here:

import diffusers
from diffusers.dependency_versions_table import deps
import inspect

all_classes =  inspect.getmembers(diffusers, inspect.isclass)

for cls in all_classes:
    # if dummy module check that all backends are in deps
    if "dummy_" in cls.__module__:
        for backend in cls._backends:
            assert backend in deps, f"{backend} is not in the deps table!"

[patrickvonplaten]

The github workflow yaml looks good, we should change the test however. Can you try to add two tests that looks as follows:
https://github.com/huggingface/diffusers/pull/3847/files#r1238267507
maybe?

[sayakpaul]

@patrickvonplaten thanks!

Currently, one test is failing for MidiProcessor, complaining note_seq is not there in there in the dependency table. I can add it, however, wanted to check first.

Edit: Strange. The failing test here didn't fail on my machine locally.

[patrickvonplaten]

Looks great! Let's merge it :-) Thanks for iterating

[patrickvonplaten]

Very cool!