which one? Provide examples

Tests case raising an error on valid code

Missing some test cases to be good

One map for sure. Not sure why I did that. Thanks for pointing it out!

Nice and clean way !

However i got a question (i'm relatively new to ruby) :
Performance wise, what's the better between :
.map{|n| n.to_i.even? }
And
.map(&:to_i).map(&:even?)

Thanks