Test that TensorFlow is not imported on startup

[lhoestq]

TF takes some time to be imported, and also uses some GPU memory.

I just added a test to make sure that in the future it's never imported by default when

import huggingface_hub

is called

[adrinjalali]

Since we do lazy loading now in huggingface_hub, [almost] nothing should be imported on import huggingface_hub anyway. But I like the test.

[HuggingFaceDocBuilderDev]

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

[lhoestq]

Yup I noticed that :) Looking forward to have a new release with lazy loading !

This test is just to make sure that in the future we don't do it without noticing, as it happened in #679 some time ago

[osanseviero]

LGTM, thanks for the test!

[lhoestq]

I ended up adding pytest ./tests/test_tf*.

This is because running the keras tests at the same time would import TF, so the test would always fail.

Let me know if it's good for you

[osanseviero]

Yes, this works for me!