Why test? Seriously, why are interviews tests?
Everyone seems very worried about incompetent job candidates, but what about incompetent colleagues and managers? We act like interviews are one-way when in fact they're two-way, and the candidate needs to decide if they actually want to work for the potential employer. Does the candidate get to test the interviewers? Nobody wants to work with incompetent colleagues, and especially not an incompetent manager, which is the worst.
There are a lot of incompetent engineering managers, and indeed I would estimate that engineering managers are more likely to be incompetent than engineers, because engineers are frequently promoted to engineering managers despite having no background or training in management.
It's ok though, I'll let the manager do a take home test in their spare time.