There's alredy an abundance of katas asking you to "compare the input with some fixed values and return a string".

Using switch is not enforced.

You need to add clear decription for different choices. As of now it could be read from the test only.

I don't know if it can be done, but maybe you could force the use of switch, I've tried using ternary operator and it also passes.
Another good addition could be a default case.

Great beginner Kata! I would suggest providing more details in the instructions section so that the user doesn't have to infer the specific strings that need to be repeated for each case.