Change [Test Template] on subject line

But is there a way for us to customize that? Whenever we need to make tests, we need to our have recipients identify the email as a test. It's actually a good feature but it would be nice if we can customize it.
Anything would be nice at this point. Customer level would be nice but for us personally, we often use it just as a single customer.

Thank you for considering my suggestion :)
Some of my team mates got used to IEM and Neolane. So we normally enter [IEM Test Bat] or [Mailwizz Test BAT].

We got a lot of emails flying around either for validation or people are just in cc. It just would really be nice if immediately our collaborators would be able to identify if the email is meant for validation or it's a normal sending which they are also just part of.
I see this was never implemented (or removed again?).

Ideally there just a suffix that can be added to the original subject line to emphasise it's just a test. As per my original feature request, the ability to not just test the template but test the campaigns (using real seed data) and marking a test clearly as what it is - a test - would be great. That way all can be done within the campaign setup.
@nadworks - i think the above discussion only targeted the email templates from backend > email templates > templates.
I don't think it was ever meant to do anything with the campaign tests.