> +           (add-after 'build 'check
> +             (lambda _
> +               (invoke "guile" "-L" "." "-s" "test.scm"))))))

To support "guix build --without-tests", make this

> +           (add-after 'build 'check
> +             (lambda* (#:key tests? #:allow-other-keys)
> +               (when tests?
> +                 (invoke "guile" "-L" "." "-s" "test.scm")))))))

Greetings,Maxime.