that's a correct test but it is poorly presented both by the test output and by your print. from your message one might think that test case is a string of length 5, but that is not the case. when you outright print a string you are displaying it as text but that is not what you are interested in, you should instead be considering the precise content of the string.

test case: $1.23
Error: 123 should equal None

Above error should not occur as 123 is the correct answer, so this test case is faulty