Description is inconsistent. Each bit in n will specify whether or not to swap the case versus because 11 is 1011 in binary, so the 1st, 3rd, 4th, 5th, 7th, 8th and 9th alphabetical characters have to be swapped. You really need to describe this more carefully.

It's not obvious from the description that the bits should be in the reversed order, how about an asymmetric example instead of 1001?

number of random tests can be safely increased to ~100

do your random tests work? i get an output 'loll' should equal '' even though my function decode('loll') returns '' (e.g. if i put this case in the sample tests)

also your random tests for decode just test for character combinations, they don't check any number input as well.

Hi,

z should encode/decode with 2