Re: [PATCH] test-lib.sh: use GIT_TEST_COLUMNS over COLUMNS

From: Jeff King <peff@peff.net>
Date: Jul 27, 2021, 17:38 UTC
Message-ID: <YQBEhj/Y6m0pqOth@coredump.intra.peff.net>
In-Reply-To: <patch-1.1-f81f3911d5-20210726T235452Z-avarab@gmail.com>

On Tue, Jul 27, 2021 at 01:57:09AM +0200, Ævar Arnfjörð Bjarmason wrote:

Show 24 quoted lines

> In my c49a177beca (test-lib.sh: set COLUMNS=80 for --verbose
> repeatability, 2021-06-29) the test suite started breaking on recent
> versions of bash.
> 
> This is because it sets "shopt -s checkwinsize" starting with version
> 5.0, furthermore it started setting COLUMNS under "shopt -s
> checkwinsize" for non-interactive use around version 4.3.
> 
> A narrow fix for that issue would be to add this just above our
> setting of COLUMNS in test-lib.sh:
> 
> 	shopt -u checkwinsize >/dev/null 2>&1
> 
> But we'd then be at the mercy of the next shell or terminal that wants
> to be clever about COLUMNS.
> 
> Let's instead solve this more thoroughly. We'll now take
> GIT_TEST_COLUMNS over COLUMNS, and furthermore intentionally spoil the
> COLUMNS variable to break any tests that rely on it being set to a
> sane value.
> 
> If something breaks because we have a codepath that's not
> term_columns() checking COLUMNS we'd like to know about it, the narrow
> "shopt -u checkwinsize" fix won't give us that.

I guess people running with bash won't see the test breakage (because bash will quietly "fix" the COLUMNS setting). But enough people run with /bin/sh that we'll eventually notice.

> This approach does mean that any tests of ours that expected to test
> term_columns() behavior by setting COLUMNS will need to explicitly
> unset GIT_TEST_COLUMNS, or set it to the empty string. I'm doing the
> latter in all the tests changed here.

This is rather ugly, and I'm not in general a fan of adding more test-only code into the bowels of Git itself. But it may be the least bad solution.

The only alternative I could come up with is _not_ to set COLUMNS everywhere, but instead insist on each individual test manually doing "COLUMNS=80 git ...". Setting it as a one-shot seems to be reliable enough. The downside is just that various tests will need to do so. We already have quite a few that do, but I guess anything that uses the progress meter is now subject to it.

-Peff