The test for QRandomAccessAsyncFile currently cover all existing APIs, but they run on a local FS, where the overhead of all operations is small compared to NFS.

Ideally, we need to check that it works as expected with really slow filesystems. In other words, we need to make sure that we do not block on the async operations.

On Linux we can use some FUSE implementation (e.g. https://github.com/dimkr/overheadfs) and modify it to introduce extra delays in all operations.

The potential implementations for macOS and Windows are TBD.

At first, these checks can be implemented as a manual test.
We can think about converting them to actual unit-test at some platforms later (e.g., it might be relatively easy to do it on Linux).