100%, however, still impressive how simple it could have been done if we were to guess the string would be so short haha

Added

Random tests added to Ruby

Can you explain why flatten is better?

Thanks, Added.

Give me more information. Do you get an exception? Whats not working about the code?

Thanks! Should be better now.

cheers! btw I think it's something to do with the CodeWars testing environment. I had to move your MySuperTest class inside the describe block to get it in scope.

I'm a little confused as to the error you're reporting, because find_the_ball(1, []) is not one of the test cases. There are no test cases for Ruby with an empty swaps list (although returning the start position would be the correct solution if there was).

...Aha! Got it. Multiple tests used the same swaps array. But your solution mutates that array, which means that the second time it's used the test that's being run doesn't match the test it thinks is being run.

I've changed the tests so that this should no longer be an issue, but I would point out that it's poor practice to mutate the array passed in like that, for precisely this reason - it can lead to hard-to-find errors.

That's not a solution to the problem. Have a look at mcquackers' earlier comment and see if that helps clarify things.

If you still think there's a problem with a test, can you tell me which one?

can you suggest how to improve it? This is my first kata so I didn't really know what I was doing.

It seems that in your solution 'observed' is a string but it is an int, doesn't it?

Convention that denotes an unused variable that is passed to the block. It actually has a special syntactic meaning in that it's the only variable name that can appear multiple times, e.g. [].map.with_index { |x, x| } is invalid while [].map.with_index { |_, _| } is valid.