Still having same issue here.
Most tests work fine, except when "not" is introduced, it seems.

im facing the same problem.

test.expect(not xo('xxxoo'), 'False expected')
             not    False             ^ 
                True            This is only shown if xo('xxxoo') returned True and not xo('xxxoo') was False instead

Thank you for your response, I'm sorry I'm not sure what you mean by that? I'm not getting an error message, my question is about why the test question expects False when the negation of the ox statement should be true.

So far, you understood how it works. The error message is shown if the first argument of test.expect isn't True.

No, it isn't, read how match works.

This this is telling me str.match() does not have a length property, that's wrong

Hello! Am I being totally daft? For the 3rd example it says: 'test.expect(not xo('xxxoo'), 'False expected')
However xo returns a bool saying True for same number of x's and o's
This means that xo('xxxoo') should return False (as the numbers are not equal) meaning that not xo('xxxoo') should return True (negation).
I'm obviously missing something.
Help very much appreciated.