you don't have to "filter out", you have to "extract" the words:

" //wont won't won't " => ["wont", "won't", "won't"] extracted, so ["won't", "wont"] as an output

invalid issue:

• without the actual input and your output, it's impossible to tell if that's an issue in the tests or if your code is just wrong.
• language?

for instance, those values are the frequencies of occurences of different words. So [25,25,23] means that there are 2 different words that occur 25 times and another that occur 23 times. While your ouput matches words that do not occur the right amont of times. I'd bet on your code not cutting the sentence correctly.

Frequencies of the returned words are compared to the frequencies of the expected words - I don't see any issue.