Initial solution includes superfluous function.

Tests are using Test.expect.

Needs random tests

I'm hoping you haven't abandoned your kata. It's a nice level of challenge, but appears to be easily brute-forced to solve. You might be able to deliver dynamic argument names if you use the Function constructor method.

I enjoyed this kata. A few ideas for improvement:

• As others have said, the tests need a lot of elaboration to make this a worthwhile exercise, though.
• You could add function calls that have more parameters than the function was expecting to make sure the coder is paying attention.
• I would emphasise the optional when referring to the excluded keys.
• You shouldn't really have example code in the initial solution code. You've got it in the description and, if anything, it could go into the example test fixture instead.