Re: bin/58570: ATF_CHECK_ERRNO semantics and/or documentation is confusing

[Robert Elz <kre%munnari.OZ.AU@localhost>]

The following reply was made to PR bin/58570; it has been noted by GNATS.

From: Robert Elz <kre%munnari.OZ.AU@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: bin/58570: ATF_CHECK_ERRNO semantics and/or documentation is confusing
Date: Sun, 11 Aug 2024 01:31:50 +0700

     Date:        Sat, 10 Aug 2024 16:45:02 +0000 (UTC)
     From:        Christoph Badura <bad%bsd.de@localhost>
     Message-ID:  <20240810164502.0E8C81A9244%mollari.NetBSD.org@localhost>
 
   |  No, it is trying to say that it checks that if foo() == -1, then (errno ==
   |  EWOTSIT).
 
 Yes, it tests that, but it also expects that foo() will return -1, and
 if it doesn't, the test has also failed.
 
   |  I believe the idea is being able that if something fails, errno has the
   |  expected value.
 
 Yes, but to test that reliably, the something has to actually fail.
 
 If something is coded (in a test) to fail, one might expect the test
 writer to know why it should fail, and hence which errno value should
 be produced.   Testing something that you expect might work (and hence
 must at least be plausibly correct) would make it difficult most of the
 time to know what might cause the error when it fails, and hence which
 errno value to expect.
 
 kre