Re: [PATCH 2/2] test-lib: teach test_seq the -f option

> On Mon, Jun 23, 2025 at 01:27:07PM -0400, Todd Zullinger wrote:
>> I don't know whether it's worth the extra code or not.  I
>> just wondered about how it would fail in the face of a minor
>> typo.  It certainly should cause any test to fail if it were
>> to output 1 instead of the intended format string, so it's
>> arguably fine as-is.
> 
> Hmm, maybe. I notice that "seq" itself does this (though it did surprise
> me). I think there it is actually doing the "%" interpolation itself (to
> avoid memory errors by feeding arbitrary strings to printf functions),
> so it's easy to do.
> 
> In our case, we can rely on the shell printf to do something sensible if
> fed garbage. And because we're not parsing ourselves, a pattern like you
> have above isn't totally accurate (e.g., consider what it would with
> "%%d"). But it probably would be enough to catch typos.

> It would also disallow:
> 
>   test_seq -f "same line" 50
> 
> to produce repeated lines, though I don't know how valuable that would
> be. So I dunno.

> If people are going to use "-f%d", I think we'd be better off making it
> work than trying to complain about it. But I was hoping we could just
> keep things simple and stupid, given the limited audience.
> 
> So my inclination is to leave the sharp edges and see if anybody gets
> cut, but it's possible that I'm just being lazy.