Re: [PATCH RFC] tests: add feature probing

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Wed, Sep 06, 2023 at 12:04:40PM +0200, Florian Westphal wrote:
> Thomas Haller <thaller@redhat.com> wrote:
> > On Mon, 2023-09-04 at 10:53 +0200, Florian Westphal wrote:
> > > Thomas Haller <thaller@redhat.com> wrote:
> > > > 
> > > > 
> > > > But why this "nft -f" specific detection? Why not just executable
> > > > scripts?
> > > 
> > > Because I want it to be simple,
> > 
> > It does not seem "simple[r]" to me. The approach requires extra
> > infrastructure in run-test.sh, while being less flexible.
> 
> I can add bla.nft and use nft --check -f bla.nft.
> 
> Or, I can add bla.sh, which does
> 
> exec $NFT -f - <<EOF
> table ...
> EOF
> 
> I see zero reason why we can't add scripts later on if there
> are cases where flat-files don't work.

Agreed, we need this flexibility.

> At this point, its just more boilerplate to add a script wrapper
> around the .nft file.
> 
> > > I could do that, but I don't see the need for arbitrary scripts so
> > > far.
> > 
> > When building without JSON support, various tests fail, but should be
> > skipped.
> > 
> > Could we detect JSON support via .nft files? Would we drop then a JSON
> > .nft file and change the check call to `nft --check -j`?).
> 
> No, but the test that should be skipped can do
> 
> $NFT -j list ruleset || exit 77
> 
> as first line of the script, no need to load any files, nft will fail
> with error in case its not built with json support.

This is fine to start with.

> > Or maybe detection of JSON support needs to be a shell script (doing
> > `ldd "$NFT_REAL" | greq libjansson`)? In that case, we would have
> > features-as-shell-scripts very soon.
> 
> Sure, I see no reason why to not have both.  The flat files have the
> '*nft' suffix for a reason...

I think this feature approach you propose is good enough and it is
rather incremental and small.