Nice kata of the series, well done.

Scala translation

yeah it makes no sense... i would think that null would be a better

What is the reason to have an empty array as an argument in one the tests when Node isn't even similar to an array?

Since this seems related, I'll piggy-back here... Python now has a fixed sample test with an empty array as input and an expected output of an empty array. Considering the proper input for the function is a Node object, not an array, it seems like this should throw an error rather than be treated as an empty tree.

if(tree.length > 0) {

trees do not have a length property in this kata

The context is non-sensical: a tree having children defined as a list should NEVER have anything else than a list for the children property. A leaf is just a node with an empty list. Using None/null/... or anything that isn't a list (or at the very least an iterable, let's say) just implies the initial design is... bad.

So:

• empty nodes must be replaced with empty lists/arrays
• explicit tests with an empty tree must be added as fixed test
• the random tests must be updated and tweaked a bit so that some empty trees will be sent to the user.

Cheers

Approved :)

JavaScript translation (author gone)

the original Python solution cannot handle empty trees (aka None). i dont know if such a test should be added ?

done

done

done