Testing live dev formats

Guide for testing against bleeding edge version of latex-dev

Package authors testing code against new versions of LaTeX may want to check out the ‘live’ code before it is official released to CTAN.

The simplest approach to doing this is to install latex locally and then rebuild the formats:

% within the latex2e repository
l3build install
fmtutil-user --refresh

However, in doing so the user's texmfhome folder will have quite a number of files added to it and the new formats will now take precedence over the installed ones. Nonetheless, this can be undone by:

l3build uninstall
fmtutil-user --refresh

The main disadvantage of this approach is that the continual re-generation of formats takes some time if code needs to be tested against both CTAN and ‘live’ code.

Custom formats to generate

Most testing that needs to be done will not involve all formats. fmtutil can be requested to only regenerate certain formats, or a custom fmtutil.cnf file can be written. I have chosen to do the latter:

fmtutil-user --cnffile ~/Dropbox/texmf-dev/web2c/fmtutil.cnf --refresh

where the CNF file contains:

pdflatex-dev  pdftex    language.dat -translate-file=cp227.tcx  *pdflatex.ini
lualatex-dev  luahbtex  language.dat,language.dat.lua           lualatex.ini
xelatex-dev   xetex     language.dat -etex                      xelatex.ini

(these lines simply copied from the standard fmtutil.cnf file.) After running the fmtutil command, the location of the formats generate is specified with a line such as:

fmtutil [INFO]: writing formats under /Users/will/Library/texlive/2019/texmf-var/web2c

We can verify this corresponds to the directory TEXMFVAR using texdoc fmtutil and kpsewhich -var-value=TEXMFVAR.

Custom format location

If we change the value of TEXMFVAR before generating the formats, we can then easily switch between CTAN and ‘live’ versions of latex-dev.

The installation procedure then becomes:

% within latex2e git repository (top-level)
mkdir -p '~/Dropbox/texmf-dev'
mkdir -p '~/Library/texlive-dev/2019/texmf-var/'
export TEXMFHOME='~/Dropbox/texmf-dev'
export TEXMFVAR='~/Library/texlive-dev/2019/texmf-var/'
l3build install
fmtutil-user --cnffile ~/Dropbox/texmf-dev/web2c/fmtutil.cnf --refresh

Following this, no changes should be apparent when processing documents using pdflatex-dev; the CTAN version should still be used.

Using a wrapper for one of the dev engines such as the following will use the format built with the ‘live’ code:

#!/bin/bash

export TEXMFHOME='~/Dropbox/texmf-dev'
export TEXMFVAR='~/Library/texlive-dev/2019/texmf-var/'

/Library/TeX/texbin/lualatex-dev -file-line-error -synctex=1 "$1"