Maxim Cournoyer <maxim.cournoyer@gmail.com> writes:

> I'm not sure I understand correctly, but perhaps you'd want to use
> --pure, so to make sure nothing from your current environment
> interferes?
>
> But that's still leave site-start.el to look into ~/.guix-profile, I
> believe.  You could also try with emacs-minimal, which doesn't have any
> of the emacs-guix additions.

site-start.el loads guix-emacs.el, which in turn runs this piece of
code:

--8<---------------cut here---------------start------------->8---
(defun guix-emacs-autoload-packages (&rest profiles)
  "Autoload Emacs packages installed in PROFILES.
If PROFILES are not specified, use a default user and system
profiles.

'Autoload' means add directories with Emacs packages to
`load-path' and load 'autoloads' files matching
`guix-emacs-autoloads-regexp'."
  (interactive (list (if (fboundp 'guix-read-package-profile)
                         (funcall 'guix-read-package-profile)
                       guix-user-profile)))
  (let* ((env      (getenv "GUIX_ENVIRONMENT"))
         (profiles (or profiles
                       (append (list "/run/current-system/profile"
                                     guix-user-profile)
                               (and env (list env))))))
    (dolist (profile profiles)
      ...)))
--8<---------------cut here---------------end--------------->8---

As you can see, the GUIX_ENVIRONMENT is scanned for Emacs packages.  So
my test is moot.

Now I'm realizing I could have tested a smarted way:

- Make sure ~/.guix-profile does not have the packages being tested
  (e.g. expand-region here).
- Install patched Emacs + tested package to a new profile FOO.
- Source `FOO/etc/profile`.
- Run `FOO/bin/emacs` and see if the package is found.

Anyways, waiting for your next patch! :)

-- 
Pierre Neidhardt
https://ambrevar.xyz/