It's still wrong in the given java test cases, currently it's 67999990100000000019, but should be 6799990100000000019

This is very likely an old problem related to the framework. The kata has been solved many times in JS since then and the issue has not been reported anymore. Moreover, no answer in 4 years.

Closing old question, just re-raise it if you sill need an answer.

There is a useless particle <> in the translated string that needs to be deleted

I added more tests and now there's many more solutions possible, and hardcoding them is hopefully not feasible.

offtopic, it's hard to find you these days... Shiimao! call me ( joke about "i'm pregnant" here)

Random tests are fair-sized, maybe you set your recursion limit too low for all of them to pass.
Edit: I see you've completed this kata already so don't mind me.

Use console.log to check the input of the test you're failing, it's a problem with your code.
I don't know why the author/translator used assert.equal instead of Test.asserEquals in those tests.

Those inputs were not exactly the same. I think you were misreading things.

Please try again.

If necessary, copy the relevant tests ( there are 3 actually ) and paste them in a monospaced notepad underneath each other. The differences should jump at you.

none of the above: we read the description

the array input will always be a valid array (possibly of length 0)

then we read the example tests

Well, either dig into the description or dig into the stack traces. in both cases, that won't be fun... x) Note that the sample tests will provide a lot of information for what you need.

Not an issue: some of your methods types are wrong, that's all. ;)

The longest one should be "6799990100000000019" which is 19 digits. Have you seen something else?

JS version worked fine for me. Were you returning a string?

Not a kata issue. There's a mistake in your code.