Jimfs VS picocli

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.

Picocli allows using a compiler annotation processor to generate classes at compile time instead [0].

[0]: https://github.com/remkop/picocli/blob/main/picocli-codegen/...

Picocli is a pretty good one for writing CLI apps

"and there are simply no good command line input parsing libraries for Java."

Looks like author missed the most obvious and popular OSS one: https://picocli.info/

The command line example gave me the "ick". It is usually preferrable to parse the command line arguments into one instance of a custom "command class", rather than into a list of things. Like jcommander, picocli or jbock do.

Complex argument parsing needs to be auto-generated by libraries like picocli. Even if you need something custom, it'd be quicker to write an Annotation processor from scratch than editing that file.

https://github.com/remkop/picocli

"Picocli-based applications can be ahead-of-time compiled to a GraalVM native image, with extremely fast startup time and lower memory requirements, which can be distributed as a single executable file."

https://picocli.info/quick-guide.html

Using picocli to handle your command line options gives you the best chance to automatically generate an ArgumentCompleter script in the future, but won't help you today (other than possibly making your command line handling more standardized & easier).

Picocli

Then we released a JBang! and picocli based cli that would be, on any OS running a jvm runtime :

picocli : "a mighty tiny command line interface"