Check if cpu.max file is non-empty before reading

[mindflayer]

Fix for #478

[tomMoral]

LGTM!

[tomMoral]

It seems that this make some test fails: test_cpu_count_cgroup_limit.

[mindflayer]

It was a bit more complex than I firstly thought, and of course I had to try everything from an environment where Docker was setting everything up properly.
I added a way to skip the test when the environment is not configured correctly, not sure if that's what we want.
Then I added two more tests with edge cases. Let me know what you think!

[tomMoral]

Thanks a lot for investigating this.
It is indeed more complex than it looked 😅

This is just a few remarks from a quick look. The last test seems to not call the expected func?

The changes seem reasonable but I need more time to read them in detail, will try tomorrow.

[mindflayer]

The changes seem reasonable but I need more time to read them in detail, will try tomorrow.

Take your time, I had this error happening for ages. Today the hidden boyscout in me thought it was the time to stop rebooting the system just to test this project of mine. :)

[mindflayer]

@tomMoral anything more I could do for helping out here?

[tomMoral]

Overall, LGTM, the change is reasonable and well tested.

Just a few more simplification for the code

[mindflayer]

I might be wrong, but the failure does not look like something related to this PR.