Tests do not compile on Windows

[Bios-Marcel]

There are calls to syscall.Umask, which isn't supported on Windows. That test could be moved to a !windows only file.

[gtramontina]

Perhaps there's a different way of asserting that the overwritten file has the correct permissions…? I can't recall why exactly that assertion is in place, to be honest. 🤔

[Bios-Marcel]

Wouldn't calling FileMode be enough? I am a little confused as to what we need umask for?

[Bios-Marcel]

I noticed that there are a couple more tests that don't really work on windows.

#19 also plays into this. When actually using hardlinks, we can't check for correct linkage anymore, as we can't necessarily detect whether we are a hardlink, since hardlinks are basically just normal files, unlike symlinks.

A workaround would be to manipulate the file and see whether both files change.

Additionally, some of the tests make assumptions on filepaths (different separators).