bug#34070: 27.0.50; icomplete-mode candidate cycling broken for C-x C-f

[Eli Zaretskii]

> From: João Távora <joaotavora@gmail.com>
> Cc: Drew Adams <drew.adams@oracle.com>,  34070@debbugs.gnu.org,  
> monnier@iro.umontreal.ca
> Date: Mon, 14 Jan 2019 16:25:41 +0000
> 
> > Please add a test for this, if possible, so that we don't screw this
> > up again in the future.
> 
> I'd love to, but it's not exactly simple to write tests that observe
> user interaction the minibuffer with ert.  At least for me.  How would I
> go about doing that?  Any pointers/prior art?

(A stab in the dark) invoke the function bound to TAB and examine what
it produces?