tests: Add a pre-allocation test

[EchterAgo]

I used this test when diagnosing #281 and think it would be a good addition.

This tests file sizes when pre-allocating a file.

Expected values have been confirmed on NTFS, ReFS and FAT32. This test currently does not work on a SMB share with the Samba server because it reports a fixed cluster size based on a configuration option instead of getting the correct value from the underlying file system. ksmbd does not have the same issue, it correctly gets the values from the file system. So far this is untested with Windows SMB shares.

This also makes tests.py use some helpers from utils.py.

Note that currently the test does not pass yet because #281 needs more fixing.

[EchterAgo]

Note that you can also point this test to a build directory (out/build/x64-Debug for example) using --zfspath and it will use the commands from there without requiring an installation.

[EchterAgo]

Looks like checkstyle fails because we do not have openzfs@9192ab7

[EchterAgo]

See openzfs#15284

[EchterAgo]

Rebased to have the checkstyle fix.

[andrewc12]

Ahh dang. This actually looks like it might have useful things.
I can't just have terrible python code anymore huh.
I'll look over it sometime.

[EchterAgo]

@andrewc12 yea, we should work on building a bit of a test library with common functionality. I wanted to also go over tests.py and improve it a bit.

Is there any reason the tests spend so much time sleeping? I'm currently trying to reduce that too.

[andrewc12]

Mostly extra cautious to avoid BSODs
Thanks for taking a look at this. 😊

[EchterAgo]

I need to fix the Python style of this change.

[EchterAgo]

So it looks like currently we only need to wait a bit before destroy, otherwise I get the same BSOD as in #282

[EchterAgo]

So this should be ready, the failing tests are Ubuntu 22.04 which seems unrelated and test9_regression_test which is the newly added test.

@andrewc12 Did the tests.py test regex for key file ever work? I could never get the original import call to work, but I do have it working now. I still need to make the run out of drive letters test work with the zpool_create context manager. I'll put those updates into a separate PR when this is merged, see https://github.com/EchterAgo/zfs/blob/a4d1fd14300f2991bde059084a885a079be9ad6c/contrib/windows/tests/tests.py

[andrewc12]

@andrewc12 Did the tests.py test regex for key file ever work? I could never get the original import call to work, but I do have it working now.

I don't know if it ever did, I honestly cant remember

[andrewc12]

Yeah this is all good stuff.
I'll have to change the rest of the tests now to use this.

[EchterAgo]

I was also planning to update the rest of the tests, but let me know if you need any help/additions or have any suggestions for things in utils.py

I want to try to create tests for previous issues I've reported here and have since been fixed.