agreed

You said nothing more, than the clarification, of which is the expected, and which is the user's solution output. But is it not also useful for the user, to see what the value of the input was?

• The initial solution still does not compile. Get rid of the comment, add todo!()
• The assertion messages should clarify to the user what left and right are, i.e. which one is their solution, and which is the expected output. Nothing more. Also, formatting is important. Add a new line at the beginning. Hint: testing your translation with an artifically erroneous solution helps you see what assertions look like.

Addresed all points to the best of my ability

Notes:

• The initial solution needs to be properly formed such that it compiles without errors.
• Instead of just giving it some pseudo-obfuscated name, the reference solution should live privately in the tests module
• All assertions should have an assertion message that clarifies what actual and expected values were.

duplicate issue below

No random tests?

After I submitted my solution I went straight to hospital for some obvious reasons :)

This comment has been deleted.

tough nut

Beautiful, very readable. Just checked and my suspicion was right, the 3rd branch isn't even necessary.

what a sexy solution, I must admit

done

fixed

you cannot type digits

would be clearer than:

you cant return numbers.

in my humble opinion