Re: [PATCH] progress.c tests: fix breakage with COLUMNS != 80

On Wed, Jun 23, 2021 at 07:48:25PM -0400, Jeff King wrote:

On Mon, Jun 21, 2021 at 09:01:23AM +0200, Ævar Arnfjörð Bjarmason wrote:

quoted

The tests added in 2bb74b53a49 (Test the progress display, 2019-09-16)
broke under anything except COLUMNS=80, i.e. when running them under
the "-v" mode under a differently sized terminal.

Let's set the expected number of COLUMNS at the start of the test to
fix that bug. It's handy not do do this in test-progress.c itself, in
case we'd like to test for a different number of COLUMNS, either
manually or in a future test.

Hmm. So I can easily reproduce the problem here, and your patch fixes
it. But my first thought was: shouldn't test-lib.sh be handling this to
give all of the scripts a uniform environment?

And indeed, we _do_ unset COLUMNS there. So I think the problem isn't
a bad setting of $COLUMNS, but rather that in "-v" mode, the
sub-command's stderr is hooked to our tty, and term_columns() is smart
enough to use TIOCGWINSZ to get the value (at least on some platforms).

Setting $COLUMNS again in the environment fixes it, because we prefer
that value to trying the ioctl.

So I don't think what you have here is wrong (though the commit message
is a little misleading).

It is misleading indeed and needs to be updated.  I did my own
analysis and arrived to the same conclusions wrt COLUMNS being unset
vs. the ioctl() and stderr being a tty.

But it seems like the original intent of our
"unset COLUMNS" in test-lib.sh would best be fulfilled by setting it to
a known value there (like 80), rather than unsetting it.

I admit this a _bit_ of a nitpick (since as far as we know none of the
other scripts care about the terminal width), so I'm OK with this as-is
if you feel strongly the other way.

I remember one commit-graph test that does check the number of lines
in the progress output, assuming one progress line per commit-graph
layer, which breaks when we break the progress line in a too narrow
terminal.  Running './t5324-split-commit-graph.sh -v -i' in a 46
column wide terminal fails for me, but succeeds with 47 columns.

I do suggest setting COLUMNS=80 in 'test-lib.sh'.