Ah goddammit, I should have known better. Thank you.

Aha! x)

Classic pythonic mistake of yours, here. ;)
look a the following message... ;o

several things:

• I tried this call on both ref solutions and they both expect 38, not 0
• your two approaches are look different. In JS, you can end up with empty strings, splitting on target chars (I assume the "view solution" is showing me your actual solution...?) (EDIT: the ref sol in JS seems to use the same approch, tho... I guess I misunderstood soemthing about that...)
• can you check again and copy/paste the input + assertion message, plz? I'll dig further in the meantime.

Ah yes, you're right. Still pretty confusing since all the basic tests are 20 characters long.

I've passed all the tests in JS, but using the same logic in Python, I get different results. If the amino list isn't passed in , it's default to ['A','I','L','M','F','W','Y','V']. Is my logic wrong in thinking that I should simply count the number of chars that are in the amino list vs the string and taking that as a percentage?

not an issue, you misunderstood the sentence: this actually tells that there are 20 amino acids with which you can build the proteins. That's not the nombre of AA per protein (often, one protein consists of thousands of AA).

;)

.

do you get that in JS or in python? (edit: python, since snake_case... I'll take a look)

Are the tests consistent between JS and Python?

aa_percentage('CPRVPYYKKHDLQDTRHTIFHVFV'), should the result not be 38? Instead it expects 0.

Every protein consists of a long chain of 20 different amino yet some of the tests have more than that.

occurances -> occurrences

Enhanced JS random tests. Added them to python.

needs random tests in python

(at least in python) Maybe there should be at least one example test that uses rounding, to avoid surprises between testing and submitting solution?

... and returns the rounded percentage of the protein that the given amino acids make up

It seems that your reference solution is rounding down in the JavaScript random tests. Please either (1) edit the description to reflect this or (2) edit your reference solution if rounding down is not intended.