.

I made a quick fix that will behave gracefully, except when the user actually returns None. Do you think it's acceptable?

oh, forget that... (was missing your last line... Back to it...)

[Python]

Tests should fail without raising exceptions if the result is not valid.

I initially forgot the return statement and got AttributeError: 'NoneType' object has no attribute 'equal'

Python Translation

About the purity question: can't you just use different deep copies of the object? It was the cause of my failure and it is absent from the original language. Should I raise an issue about that? It's the point of tree rotations to change the tree in place.

The problem is the log shows no difference between actual and expected.

For me an array or such is not a proper way to encode a tree, but I'm just ignorant.

I don't understand the problem. The encoding is specified, appropriate, and a binary tree. Whether the specific class is Object or something custom does not really matter.

The purity requirement is mostly because modifying your arguments makes test failure messages weird, and deep-freezing inputs is not a real solution either ( as well as bug-prone ). But this was not raised as the issue anyway - if you want that changed, please raise that as a separate issue. ( I'm willing to discuss the merits, but I will not be doing it. I just don't think it's a good idea. )

Is the problem here the [Object]s? Or should I be reading something else into it?

It would be pointless if the kata was not rotate a binary tree.

JS:

expected { left: null,
  right: 
   { left: null,
     right: { left: [Object], right: [Object], value: 8 },
     value: 5 },
  value: 2 } to deeply equal { left: null,
  right: 
   { left: null,
     right: { left: [Object], right: [Object], value: 8 },
     value: 5 },
  value: 2 }

The only real difference between JS and Java versions is the added purity requirement which genuinely shouldn't be there. Objects lacking a pointless Node wrapper is definitely not an issue, though.

Please consider the issue I've raised above. I think it's still the time to rectificate.

Javascript should use a node/tree class like the other (and original) languages. Currently it just doesn't respect the kata specifications.