Hi,

> +           (lambda _
> +             ;; This test fails, I don't know why.
> +             (invoke "ctest" "-E" "parsertest"))))))

To support "guix build --without-tests=labplot" and cross-compilation,
I recommend

> +           (lambda* (#:key tests? #:allow-other-keys)
> +             (when tests?
> +               ;; This test fails, I don't know why.
> +               (invoke "ctest" "-E" "parsertest")))

here.

Greetings,
Maxime.