Refactor: use tempdir/pathlib instead of os where suitable

[valentinaschueller]

fix #49

[uwefladrich]

Good to see this!

May I jump in with an early suggestion: There are two possible patterns to use pathlib.Path:

import pathlib
# use pathlib.Path()

or

from pathlib import Path
# use Path()

The former is used in 228a8ae, however, I would vote to use the latter. Two reasons:

• It is shorter in the actual code and should never be ambiguous. At least it would be a very bad idea if we ourselfs implemented a class called Path (and we should be punished in that case).
• It is already used according to the second pattern in recent changes were pathlib was introduced.

A possible counter argument would be if we used something other than Path from pathlib. But even then I would vote for the somewhat verbose

import pathlib
from pathlib import Path
# use Path()
# use pathlib.SomethingElse()

with the understanding that this would be a rare case.

[valentinaschueller]

however, I would vote to use the latter

I agree, this is implemented in 17101ab. I finally hunted the bug down and can now proceed to update the other instances of paths/os

[valentinaschueller]

I think this is ready to go! os is left in some places but for a reason:

• test_file_handling.py: used to get the current working directory
• diskusage_rte_scalar.py: used for scandir()
• files.py: used for the ChangeDirectory context manager

I applied black + isort for everything and only touched the SI3 tasks in places where it should not lead to merge conflicts with PR #60

[valentinaschueller]

@uwefladrich regarding 1a73bf4. Do you run isort before running black? the formatting of imports was done by isort and I wasn't sure what should be the "final" tool to call

[uwefladrich]

Do you run isort before running black?

Yes, isort first and then black. The reason is that black should have the last word about style. isort should just sort the imports.

[valentinaschueller]

In the tests, I would suggest to use the tmp_path fixture instead of tmpdir, see test_file_handling.py for an example. tmp_path is a Path object and you can avoid part of the string handling for path names.

Fixed in 51fcc87. Note: I kept tmpdir in three tests since there, .mkdir().join() and .write() are used and solving it with PosixPath leads to longer and less readable code