bug#51037: [PATCH] Make `print-level` & `print-length` customizable in ERT batch tests

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael <sp1ff@runbox.com>
> Cc: larsi@gnus.org, gazally@runbox.com, 51037@debbugs.gnu.org
> Date: Sun, 14 Nov 2021 07:42:27 -0800
> 
> This commit introduces three new ert variables:
> ert-batch-print-length, ert-batch-print-level &
> ert-batch-backtrace-length. The first two control print-length
                            ^^
Please leave 2 spaces between sentences, per our coding conventions
(here and elsewhere in your patch).

> +line lengths (i.e. to get full backtraces), or a positive integer to

Either "i.e.," (with a comma), or "i.e.@:".  Otherwise TeX will
typeset "i.e." as if it ends a sentence.

> +** New ERT batch variables
> +
> +Add three variables 'ert-batch-print-length', 'ert-batch-print-level'

In NEWS we use a different style, like this:

  Three new variables 'ert-batch-print-length', ...

IOW, "Add" is not appropriate here.

>  Backtrace mode will attempt to abbreviate printing of backtrace
> -frames to make them shorter than this, but success is not
> -guaranteed.  If set to nil or zero, Backtrace mode will not
> -abbreviate the forms it prints."
> +frames by setting `print-level' & `print-length' to make them

Please don't use "&" in doc strings; use "and" instead (here and
elsewhere in the patch).

> +shorter than this, but success is not guaranteed.  If set to nil
> +or zero, Backtrace mode will not abbreviate the forms it prints."
            ^^^^^^^^^
"backtrace", not capitalized/

> -(defun ert--setup-results-buffer (stats listener buffer-name)
> +(defvar ert--output-buffer-name "*ert*")
> +
> +(defun ert--setup-results-buffer (stats listener)
>    "Set up a test results buffer.
>  
> -STATS is the stats object; LISTENER is the results listener;
> -BUFFER-NAME, if non-nil, is the buffer name to use."
> -  (unless buffer-name (setq buffer-name "*ert*"))
> -  (let ((buffer (get-buffer-create buffer-name)))
> +STATS is the stats object; LISTENER is the results listener."
> +  (let ((buffer (get-buffer-create ert--output-buffer-name)))

Why this change in the signature of the function?