I completely agree with you, however, when I spoke to EK, the guy on the phone said the test has to be in France, and I told him why - and he said that is the rule.
I am 99.9% certain such a rule does not exist. You just spoke to an incompetent agent. But I understand you don't want to take any risk, so it is safe to take a test while in France.
IFit-to-fly is used heavily in the UK I think mainly. Basically all I mean is that it is a certificate rather than just an email or a text message.
You'll definitely have a certificate.