Enable recursive directory traversal in casc

[dburgener]

This enables recursively discovering all policy files in the specified
path(s), which is expected to be the most common use case.

Additional ergonomics, like defaulting to CWD if no path is specified is
future work.

[l0kod]

I'd prefer to sort the list of inserted/walked paths (not necessarily the list of argument paths) to get consistent behavior whatever the underlying files/filesystem/host.

[l0kod]

Updating the documentation and the casc's help with this new usage would be useful too.

[dburgener]

I'd prefer to sort the list of inserted/walked paths (not necessarily the list of argument paths) to get consistent behavior whatever the underlying files/filesystem/host.

You mean sort the return from output of get_policy_files()?

[dburgener]

I pushed an update, but the only issues I've addressed so far are rebasing on the latest merges and switching from println!() to eprintln!(). I'll look more closely at the rest next week.

[dburgener]

CI breakage is due to clap. It looks like they're making this breakage opt-in in an upcoming PR: clap-rs/clap#3830

[l0kod]

It would be nice to add a test calling casc (with another PR).

[dburgener]

It would be nice to add a test calling casc (with another PR).

Yes, although I don't think that there's a clean way to do that in the current unit test framework, so we'd need to add some other test framework for it. That's fine, but it's more work, and lower priority than library testing IMO, so it may not be immediately forthcoming.