The French declaration reads that a test (which is acceptable by the French government) is compulsory from the UK whether you travel to France or transit there.
Full rules and eligibility can be found here: https://uk.ambafrance.org/COVID-19-Conditions-de-deplacement-entre-la-France-et-le-Royaume-Uni-28925.
Please check carefully as anyone not meeting the criteria will not be permitted to travel.