As a concrete example, the reason why rounding to 2 decimal places is not a panacea is there is one test where one of the values is -5.055

Depending on the order in which you do the calculations, you may get -5.05499999 or -5.055000001, which round to different results in two decimal places.

Random Tests are already added. When i'm ready with the floating point issue the tests musst be renewed. I will extend the Random test part.

The necessity of random tests is documented. You should probably read more documentation before creating your next first kata ( this one will probably be retired ).

Rounding is not a solution to floating point representation errors, comparing with an error margin is. This is documented.

I testet offline and online and got no rounding problems. I round because of floating point errors. Don't know how to clarify this.
Maybe with a precision parameter.

Don't round the results. Random tests are consistently rejecting correct solutions because of floating point errors.

Randomtests added.

It's my first cata, i will add random tests. I changed last sample test to n = -3 but unpublish,-> save - publish will go on showing wrong number 4. Sad!

Amazing Kata, thx!

Absolute annoying that we must guess which exception to be raised. Put a little more work into Kata's u created pls.

I have modified the tests so that, even if the user's code modifies the list of customers, the validation messages refer to the original customer list. I also modified the validation procedure to give a diagnostic message that explicitly compares the number of rooms used by the user solution to the correct number of rooms.
(This refers to Python - I will do the other languages as soon as possible.)

I am traveling without access to a computer, but I think what is happening is that your code is modifying the list of customers. I added something to the description clarifying that should not be done.

Once I get home I will modify the validation procedure to provide clearer debugging messages.