Hi,

>           (replace 'check
>             (lambda _
>               (with-directory-excursion "tests"
> -               (invoke "ctest" ".")))))))
> +               (invoke "ctest" "."))))

I would make this

>           (replace 'check
>             (lambda* (#:key tests? #:allow-other-keys)
>               (with-directory-excursion "tests"
>                 (when tests?
> -                 (invoke "ctest" ".")
> +                 (invoke "ctest" ".")))))

That way, "guix build libolm --without-tests=libolm" should work.

Greetings,
Maxime.