Update tests

[apoorvkh]

• move "examples" to "tests"
• also write simple tests for every failure mode (raising errors, throwing exits, etc)

[pmcurtin]

One small thing is that I'm not sure how to change the submitit script into a real pytest test.

[apoorvkh]

Oh, because submitit just submits the job to a queue and terminates?

I believe there is a blocking mechanism: see the .result() here.

https://github.com/facebookincubator/submitit?tab=readme-ov-file#an-example-is-worth-a-thousand-words-performing-an-addition

But this test would take a minute, since you have to wait for the job to queue etc.