Jimfs VS jqwik

Java has in-memory file systems that are essentially geared for this exact use case, eg jimfs[0]. You create your filesystem and any files you need when your tests are starting up, and your classes talk to them rather than the “real” ones. Maybe a similar project exists for the C++ ecosystem?

[0] https://github.com/google/jimfs

Recently been using JIMFS. Made my tests much faster and cleaner!

I use Google's JIMFS "Just In Memory Filesystem" https://github.com/google/jimfs in my unit tests and have been very happy. No need to clean something up that disappears as soon as the test is over. Let's you create unix or windows style filesystems and I've used it to test a disk space healthcheck because you can set a limit to the size of the filesystem it creates. Very flexible and easy to use.

See https://jqwik.net

Once we knew which property to use it was very straightforward to add a property-based test for it. We used the jqwik library. We like it because it has very good documentation and it is integrated with Junit.

Jqwik - I love property based testing and the way it can make you think differently about some of your code.

Different to mutation testing, but on a semi-relatednpath, I've found property-based testing (e.g. https://jqwik.net/) to be valuable - thinking about the “shape“ of the expected output and getting a bunch of pseudorandom tests is pretty handy, especially for utility functions.