Same, perhaps this answer was provided before the test cases were upgraded? Seems like answers that have been made invalid shouldn't be kept on this page.

I appreciate this solution, but when I attempted the +1 Array challenge for my 2nd time, I pretty much copied and pasted what you did. Upon executing it, I saw that 3 test cases failed and I couldn't figure out how to remedy this despite my best efforts.

use each_with_object instead